A buddy of mine dated a chick with HPV (genital warts) and he didn't have a clue. Would go down on her all the time. Asked her "what's that thing next to your anus that's growing" and she said, "it's just a mole".

He ended up with HPV all over his tongue and throat. Literally had to have them cauterized off.
Several times since they kept coming back.
A few years later a friend called him up and said if you ever have the chance to hit "so and so" again DON'T because she has herpes. He asked how do you know and he said my wife is a nurse at the clinic and she's being treated there.
So he's got that going for him (Missing getting herpes that is) LOL