It’s no great mystery that sex can be a risky proposition; that risk only climbs if it’s unprotected.

Most of us grasp the potential dangers of unprotected sex — namely an unwanted pregnancy with heterosexual sex, and sexually transmitted infections (STIs) for everyone, regardless of orientation. In the case of the latter, there’s a shortlist of microbial baddies that are explicitly linked to sex: HIV, chlamydia, gonorrhea, and herpes simplex type 2 to name a few. But while the above germs certainly represent the lion’s share of STIs in the U.S., there are plenty of obscure and otherwise unexpected diseases that can also discreetly tag along during sex.

Click the slideshow above to see some of these surprising culprits.