Q: I have been seeing a man casually for two months. We have sex about twice a week, when we have time to see each other. Last weekend we were both a little tipsy and had fun, sloppy sex. Everything was fine until he put it in my vagina right after putting it in my butt. No changing of the condom, no washing in between. I just sort of went with the flow and let it happen, even though I know you're not supposed to do that. Do I automatically have an infection now? I don't want to go to the gynecologist and explain what happened and have an exam for no reason if nothing is wrong.

A: I'm glad you're aware that this kind of double dipping is a no-no. Sticking any kind of object in the vagina immediately after it's been in the anus is one of the easiest ways to score yourself a urinary tract infection (UTI) or a case of bacterial vaginosis (BV). Your colon is filled with E. coli, a strain of bacteria that's basically harmless, provided it stays where it belongs. Sneak some of that stuff out the back door and all hell can break loose. Once it's transferred outside the anus, E. coli likes to nestle up in the vagina or urethra and wreak havoc.

I know what you're wondering: Can dudes then get UTIs from unprotected anal sex? Why, yes, they can (and what an excellent question)! It's much less common, but it can happen. That's why it's best not to go bareback when doin' it in the butt; a male or female condom will help prevent UTIs, not to mention other sexually transmitted infections, in both partners.

Most UTIs occur in women; E. coli is responsible for more than 80 percent of UTIs, and BV is the most common type of vaginal infection, so there's a good chance that something's not right in ladyland. The symptoms of a UTI are fairly easy to recognize: a painful or burning sensation when you pee, a feeling of pressure in the lower abdomen, a constant urge to urinate and urinating small amounts constantly. If any of that sounds familiar, head to the doctor for some antibiotics. BV gives itself away easily with a watery, fishy-smelling discharge. This can also be diagnosed by a doctor, although many women find home remedy more effective than antibiotics. See my March 11 column ("Odor eaters") on curing BV without prescription antibiotics.

Don't worry about what the gyno will think. You don't have to explain that you've been having anal sex, just say that you've been sexually active and want to make sure everything is OK down there. BV and UTIs are ridiculously common, and far from the worst thing your gyno will see that day.

Q: After what age does the penis stop growing? Is it the same duration of puberty or what?

A: The penis reaches its full size when the whole man reaches his full size, generally considered the indicator that puberty is over. Since everyone's body is different and we all start and stop puberty at different ages, there's no magic number to determine when everybody (and everything) is done growing. Some people cap off at 17, others not until 22.

Until I got your question, the strife an adolescent boy must feel as he stands naked in front of the mirror every night, staring at his below-the-waist reflection, never occurred to me. I imagine he privately tries all sorts of futile tactics to elongate his little member. Pulling it up, yanking it down, rolling it between his palms like a Boy Scout trying to start a stick fire. To all my future hotties out there: Give it up. There's nothing you can do to increase the size of your penis. Only Mother Nature is in charge of your little soldier, a fact that will continue to frustrate you for the next several decades.

  • Alexis McKinnis is taking your questions about sex, dating and relationships. Send them to advice@vita.mn or submit anonymously at www.vita.mn/alexis. Don't leave out the juicy details!