DEAR ABBY: I have a father who's always mean to me. He finds reasons to yell at me -- for example, the trash isn't taken out or the dishes aren't washed. He isn't involved in my educational life at all. When my teachers request a conference with my parents, he almost never shows up. When I graduated from elementary school and middle school, he didn't come to either of the ceremonies.

I'll talk to my dad about these things sometimes, and he says he's sorry and the next day he'll buy me something to try and make it up to me. He can be really nice when he wants to be, but most of the time he's a mean person. He is always putting me down, calling me an idiot and saying I'm worthless and a good-for-nothing son. I really want to become friends with my father, but it seems he doesn't. What can I do? -- WANTS A FATHER IN SOUTH CAROLINA

DEAR WANTS A FATHER: You may not be the perfect son, but you are not good-for-nothing, worthless or an idiot. What you have described is sad, because this may be a "parenting technique" your dad learned from his own father. I don't know whether he's an alcoholic, a workaholic or what other reasons there may be for his absence and his guilt. But "Father of the Year" he's not, and if you want a male you can look up to, you will have to find one elsewhere. Talk to your mother about this if you haven't, and ask her to guide you. You have my sympathy.

DEAR ABBY: My son and his girlfriend of 13 years, "Liza," broke up, and my son has moved out of the house they bought together. They still have a lot to settle, but so far, they remain on reasonably good terms.

The news of their split has left my wife and me feeling bad. We developed a bond with Liza over the years and we are unsure how to proceed from here. We feel she has become a part of our family, especially since she has no real family of her own.

We would like to express our sorrow for their breakup, wish her the best in the future and, perhaps, maintain friendly contact. We do not want to upset our son by doing this.

Please advise me on how we should proceed. What is the proper approach for parents and other family members in this situation? -- CAUGHT IN THE MIDDLE IN OTTAWA

DEAR CAUGHT IN THE MIDDLE: You're asking the wrong person. The person you should discuss this with is your son. While it is understandable that you feel Liza is a member of the family, the truth is she isn't in the literal sense. The extent to which you keep her in your lives may depend upon the circumstances of the breakup. While the extended family may wish to maintain relationships with her on an individual basis, whether your son would be comfortable having her present during family holidays is yet to be determined.

DEAR ABBY: I am 17. My 15-year-old sister and I know each other's thoughts and feelings almost as well as our own. Unfortunately, we also know when the other's funny bone is "tickly" -- and it starts a giggling fit. When we start, we can't stop.

We get these fits at the most inappropriate times. We are at our wit's end. Can you help? -- GIGGLE GIRLS IN LANCASTER, PA.

DEAR GIGGLE GIRLS: Yes. When you know something is funny, but it is inappropriate to start giggling, the two of you should not make eye contact. That will solve your problem.

DEAR ABBY: My adult son passed away nine months ago. I am mostly numb. My home has always been welcoming, and I have had friends and family here constantly -- but now they won't leave! They don't seem to "get" the fact that I need some time to be alone.

I love these people, but my heart is broken. The only person I want to see and spend time with is my surviving son. I have lost my enthusiasm for almost everything. I work full time and no longer want to be the "hostess." I am tired. My sons and I were close, and I raised them by myself.

How do I tell my friends and family members that I need to be alone without offending them? I want to do the right thing. -- HEARTBROKEN IN CORPUS CHRISTI, TEXAS

DEAR HEARTBROKEN: Please accept my deepest sympathy for your loss. I'm sure your friends and family care deeply about you and are only trying to be there for you.

However, you need to heal as best as you can in your own way from the death of your son. Thank them for their constant support, and explain that you need some time to be alone and cope with this without a crowd around. They will understand.

Working your way through the grieving process can be exhausting. But if your "tiredness" persists, I'm advising you to discuss it with your doctor because it can be a symptom of chronic depression, which is a medical condition.

DEAR ABBY: I'm a friendly, outgoing cashier at a grocery store. I enjoy chatting with customers. I particularly like some of them and look forward to them coming in. The problem is what I should do when they ask me for personal information, like my phone number or Facebook information.

In the last month, two customers asked to be my friends on Facebook and one asked for my phone number. I don't feel comfortable sharing this information with them. It's important for me to have a private life kept separate from my work life.

What is a polite way to let them know I don't want to give out that information? -- FACEBOOK-UNFRIENDLY IN LOVELAND, COLO.

DEAR FACEBOOK-UNFRIENDLY: Smile at the customer and, in your usual upbeat, friendly way, say: "You know, I think you are very nice -- but I keep my work life and personal life separate. I never mix the two. But thanks for asking." Period.

DEAR ABBY: My 12-year-old daughter, "Sophia," repeatedly shirks her basic responsibilities. She routinely receives detention for not completing homework assignments and for failing to bring required materials to class. Despite my concern, Sophia continues with her usual shortcomings. This is causing a great deal of stress between us, and our relationship is now very poor. Should I keep pushing her or should I just allow her to fail? -- DISAPPOINTED MOM IN LOUISIANA

DEAR DISAPPOINTED MOM: Of course you shouldn't allow your daughter to fail. All mothers have to "push" sometimes. It goes with the territory. However, rather than letting it drive you and your daughter apart, talk with her teacher and see if she or he can give you some insight as to what's going on. If that doesn't help, then consult Sophia's pediatrician. The girl may have a neurological problem that's causing her behavior.

What teens need to know about sex, drugs, AIDS and getting along with peers and parents is in "What Every Teen Should Know." To order, send a business-sized, self-addressed envelope, plus check or money order for $6 (U.S. funds) to: Dear Abby -- Teen Booklet, P.O. Box 447, Mount Morris, IL 61054-0447. (Postage is included in the price.)

DEAR ABBY: I live in a dorm at a large university where a former friend, "Glen," also lives. We are no longer on speaking terms because of an incident that happened last year.

One day during pre-finals week, I left my room briefly to get something from a friend's room down the hall. I left my door unlocked because I'd be back soon. When I returned a few minutes later, my laptop, my cell phone and several books full of class notes were missing. I was distraught almost to the point of a breakdown.

Later that night, Glen knocked on my door and revealed that he had hidden the items in his room to "teach me a lesson" about not locking my door. I was speechless that a "friend" could do such a thing to me.

I notified the police and officials at the university. Glen was arrested for theft and charged with a misdemeanor. The university terminated his scholarship, and he was sentenced to community service.

Glen is now blaming me for what happened. He claims what he did wasn't really "stealing" and that I ruined his life. He's harassing me at every opportunity and spreading misinformation to my friends.

I believe I acted justly to what was plainly a case of theft. Am I wrong? How should I act in the case of Glen's current behavior? -- VICTIM IN TEXAS

DEAR VICTIM: Your former friend appears to be emotionally disturbed. He has no one to blame but himself for what has happened to him. If you haven't already done so, warn him to stop the harassment -- and if he doesn't, report it to the authorities. And don't worry about the misinformation he is trying to spread among your friends. If they are truly your friends, they'll believe you when you tell them they're being lied to.

DEAR ABBY: My husband and I have been arguing about his leaving the lights on throughout our house. He's convinced that it adds little to our electric bill, but it bothers me that every single light is left burning. I realize there is a cost difference between incandescent and fluorescent lighting, but leaving all the lights on seems unnecessary and wasteful to me. Could you please "shed some light" on our argument? -- LIT UP IN JOHNSON CITY, TENN.

DEAR LIT UP: According to the Renewable Energy Policy Project (REPP) in Washington, D.C., leaving a 100-watt incandescent bulb on for 12 hours a day for one month will add $40 per year to your electric bill. Multiply that by the number of bulbs in your home and it can add up quickly.

Fluorescent bulbs use fewer watts than incandescent bulbs, but turning them on ages the filaments -- so if they'll be turned on again within a minute or two, leave them on. (This is not a recommendation to leave fluorescent bulbs burning constantly, just a suggestion that if they won't be needed after a few minutes, to turn them off.)

LED bulbs are more expensive to buy, but they last longer, use less wattage and emit brighter light. However, when the illumination is no longer needed, they, too, should be extinguished.

P.S. Since your husband has money to burn, why not invest in motion sensors so he'll have light wherever he goes without inflating your energy bills?