I live in Prague, Czech Republic — Europe. Before asking any question, I should tell you that I really appreciate your service. As for my question, I would like to ask you about the most common reasons for condom failure as a contraceptive method. I suppose that the most frequent one is condom breakage. But what are the others? I am especially concerned about pregnancy risk implied by the accidental transfer of sperm in pre-cum to condom by fingers while putting it on.

I am a twenty-one-year-old virgin who has just recently started seeing a girl very seriously. I am frustrated at how my body reacts to the slightest physical stimulus. Holding hands, talking about physical affection, even thinking about kissing gives me an erection. I am not thinking about sex, and we are not going to have sex until we are married, but I can't believe how frequent these erections are. I know it's common for guys my age to have erections, but just being with a girl I care about gives me one, and it's not easy to hide, and I don't want her to think the wrong thing. I used to masturbate and view pornography a lot but I finally stopped because I didn't agree with it. I stopped about the same time I met her. Do you think that my past is causing my body to want something I'm not going to give it?

I would wish to know about the health implications of men using vibrators. I seem to have developed a fungus/mold. I would like to know more before a health check, approaching in complete ignorance. Thank you.

If you were a woman, who wanted to be a man, could you get a penis? And once you got your penis, could you masturbate, ejaculate, and experience other male sexual behaviors?

And vice versa. If you were a man, who wanted to be a woman, could you then get your penis removed, and then masturbate?

I've read some other questions on here about men hitting the cervix with their penis and that the penis doesn't go through the cervix. I'm larger than average and my girlfriend is telling me that I'm actually going through the cervix. When we first started having sex it was very painful for her because she thought that I was penetrating the cervix. Now she's past it being painful but still thinks that I'm actually penetrating the cervix. My question is, is that possible?

PLEASE, PLEASE, PLEASE answer this question for me. Are condoms you buy from machines in the bathroom safe? What I mean is, could they carry some sort of disease or STD or anything that can make me sick (I don't mean allergies)? And also, could you tell me if American condoms are better than other countries' condoms? I read that U.S. condoms are electronically tested for defects or diseases, but I was wondering if other countries like Europe or Thailand or whatever tested their condoms, too. If I was older, I would buy condoms from boxes, but until then, I am stuck buying them from bathroom machines.

My boyfriend likes to wear my underwear. Not just before we have sex, but just all the time. He's not gay or anything, he says he just "likes the way it feels." Is this normal? Is it something that all guys go through? Should I be worried? It doesn't bother me. I actually kinda think it's sexy, but I was just wondering if there was something else going on?