Man, I totally almost fucked this girl who wanted me real bad... but didn't get around to it. A year later, I'm doing her sister, but not before her sister had to make sure I didn't do the first girl - turns out the first one supposedly has genital warts. I saw her stuff and there was nothing with it, so I guess the sister could just be making it up because she's a possessive bitch and doesn't want me messing around with the first girl... but hell, that puts enough doubt in my head not to ever have sex with the first girl.
My wife would be pretty mad if I gave her an STD I got from someone else.