DEAR ABBY: My sister, "Joni," caught me having sex with my boyfriend. (We used protection, so it's not like I'm going to get pregnant.)

Our parents were away and Joni was supposed to be gone for several hours, so I thought we would be safe. But Joni had a fight with her boyfriend, came home sooner than we expected and caught us "in the act."

Now she's blackmailing me. I have to hand my allowance over to her -- and that's not all. She has turned me into her personal slave -- changing her bed, picking up her dirty clothes and doing her chores. She forces me to let her wear my nicest jeans and shirts, but because she's bigger than me, my clothes are getting stretched out of shape or torn at the seams. When I complain, she says, "What are you going to do about it? Go ahead and tell Mom and see what I tell her!"

I know if Joni tells our parents they won't let me see my boyfriend anymore. We're in love, and I couldn't handle that. But the blackmail is driving me crazy. Please help me. -- BLACKMAILED IN AMES, IOWA

DEAR BLACKMAILED: Part of being sexually active is being mature enough to be responsible about it -- and that includes not only making sure you won't become pregnant but also that you won't contract a sexually transmitted disease, some of which, I am sad to say, are rampant today. Because you are sexually active, you should now have regular checkups by a gynecologist and possibly be using a second form of birth control because condoms have been known to fail.

That is why it is important that you confide in your mother. Once she knows, your sister will have nothing to blackmail you about.

DEAR ABBY: My husband and I disagree about something. When we use a restaurant coupon, how should we figure the tip? I say you should tip on what the total would have been if you didn't have the coupon. He says we tip on the discounted amount. It is unpleasant to go out anymore because we end up arguing at the end of the meal. Who is right? -- COUPONING IN NEW MEXICO

DEAR COUPONING: You are. Your husband is already getting a good deal because he is getting a discount. For him to expect the server to suffer a loss in gratuity income is stingy. How would he feel if the person brought out only one entree and let him pick up his from the kitchen? Not too pleased, I suspect.

DEAR ABBY: My wife and I have been arguing about relationships after marriage. My daughter was married a while ago, and I have been told that now I must consider her in-laws as "family."

That's not the way I remember learning it. Yes, my daughter is now related to her husband's parents by marriage, but since when is there a "dotted line" connecting them to me? -- UNRELATED IN MICHIGAN

DEAR UNRELATED: The "dotted line" is the umbilical cord that connected your daughter to your wife and the heartstring that connects you to your daughter. So warm up and get with the program, or the person on the outside will be you.

DEAR ABBY: I would like to comment on the letter from "Once a Mechanic ... in Arizona" (Dec. 24), who still dreams about his job even though he is now retired. I once worked in the customer service department of a major retailer. During one Christmas season, a recurring dream would interrupt my sleep each night. In my dream, my bedroom door would open and a stream of customers would file in and line up next to my bed, their arms loaded down with purchases or returns.

After many frustrating nights of restless sleep, I finally figured out a solution. I envisioned a flashing neon sign on my headboard that read: "Lane Closed." The following night when the customers began filing in, I took control. I sat up and pointed to the flashing sign above my bed. The customers turned around, walked out the door, and my sleep wasn't disturbed again.

"Mechanic" needs to acknowledge that it is only a dream and direct it on a different path, as you suggested, by thinking about his hobbies or his family. Dreams are a part of our subconscious, but that doesn't mean we can't control their content. -- DREAM WEAVER IN MANITOWOC, WIS.

DEAR DREAM WEAVER: Thank you for sharing your solution for achieving peaceful slumber. Allow me to offer another: Each night before I fall asleep, I say my prayers and count my blessings, one by one. "Sweet dreams are made of these ..." Read on:

DEAR ABBY: A rich and blessed retirement sounds wonderful. If the dreams of "Mechanic's" lifelong trade persist and he finds he really misses working, there is a way to honor that gift while still enjoying his retirement. He should check around to see if there are any mentoring programs in his area offered through social services. I'm sure many teens and young men would appreciate knowing someone with his skills. -- JAN IN SPRING, TEXAS

DEAR ABBY: I have a master's degree in physics and have been known to solve calculus problems in my dreams. "Mechanic" should understand he is not alone, and probably was very good at his job. -- A.J. IN LITTLETON, COLO.

DEAR ABBY: I used to work in several demanding areas at a manufacturing plant, and I would often dream about being unable to keep up with production. Finally, I learned to relax and say, "Let the night shift do it!" Then I would be able to move on to a better dream. Now that I'm retired, I still dream occasionally about going back -- but only to visit, never to work. -- DAYDREAMER, OLIVET, MICH.

DEAR ABBY: Because "Mechanic" enjoys doing transmission repairs even though he is retired, perhaps he could make some sort of arrangement to offer his expertise to low-income families who have cars in need of repairs. It would be a way of helping people with a need while doing what he did for so long and misses. -- A FELLOW ARIZONAN

DEAR ABBY: I have been dating a wonderful man I'll call "George" for the past 14 months. We have never had an argument or even a disagreement. We both have good jobs, like doing the same things, and we see each other every weekend. Our co-workers and family members have commented that we seem remarkably happy as a couple.

Don't get me wrong. George and I know what we like and dislike in life. We talk about things, have serious discussions and deal with whatever comes our way. But for some reason, my sister insists that by now my boyfriend and I should have had at least one good argument. She thinks it's weird that we haven't, and says we are "trying too hard" to make each other happy. She says George and I are ignoring things that could cause unhappiness.

My sister is younger, married, works full-time and has three kids. I think she may be secretly jealous of our relationship. So I ask you, Abby, DO all couples have to argue or have disagreements? -- "MISS BLISS" in N.Y.C.

Dear "MISS BLISS": No, they do not. Some couples have a higher compatibility quotient than others. Intelligent, mature people do not necessarily agree on everything. However, they respect each other's right to disagree without it degenerating into an argument.

It appears that you and George recognize how lucky you are to have found each other. Whether your sister is jealous is beside the point. When you are ready to take the next step, premarital counseling -- which I think is a good idea for all couples -- can ensure that you and George are on the same page about the things you both think are important.

DEAR ABBY: Our 10-year-old son, "Harry," is a sore loser. If we play a sport or a board game with him, he ends up in tears if he doesn't win. Sometimes he will cheat if he thinks it will help him win. He even becomes upset when his favorite NHL hockey team loses a game.

We have told Harry repeatedly that games are supposed to be fun, but he seems unable to grasp the concept. We do not know what else to do. Can you help? -- HAVING NO FUN IN CANADA

DEAR HAVING NO FUN: Learning to handle and channel frustration is part of growing up. Nobody likes to lose, yet winning and losing are a part of every competition. If you catch Harry cheating, there should be a penalty, and you should let him know you are disappointed in him.

Continue to impress upon your son that the most important aspect of sportsmanship (or gamesmanship) is learning not only to be a gracious winner but also to be gracious in defeat. Tiger Woods is a glowing example of sportsmanship at its best. A cheat may win a game, but when the deed is discovered, no one respects the person. It's sad to say, but we have seen examples of that, too, in professional sports in recent years.

DEAR ABBY: Why is it that men, no matter their ages, are jerks? I am a single mom and have been divorced for two years. I date occasionally, and when I do, I try to date good guys who could possibly become more.

Abby, I never get a second date! I am sweet and can carry on a conversation. I go out with them or cook for them. I just don't understand why they never give me a second chance. -- HURT IN ROSWELL, N.M.

DEAR HURT: Not all men are "jerks." Because you are consistently getting the same reaction from every man you date, it is time to seriously consider what you might be doing to chase them away. A good place to start would be by having a frank talk with some of your male relatives and/or platonic friends.