|both. Herpes or any other std, including hiv.|
hmmm. I'd like to clarify the hiv thing a bit. Hiv would be quite low here. I read that there's never been a clear incident of oral hiv transmission. The *estimated* risk is like 1 in 10000 with somebody known to be hiv positive.
Having said that, you biggest concern is herpes. Type 1 is the kind that is generally on the mouth and causes cold sores. Type 2 is the genital type. However, either type can show up in either place. Its just that type 1 has an easier time on the mouth and type 2 on the genitals. Its possible to pass it.
Other stuff is possible. I'd say just try to be careful and not worry about it excessively.
the question wasn't, "how likely is it to happen," but rather "could it happen?"