No, its not some kind of deviant gorillas in the mist story, apparently,
millions of years ago our ancestors picked up pubic lice (crabs) either by
sleeping in gorilla nests (without the gorilla) or through eating our
silver-backed cousins. David Reed and colleagues at the University of
Florida publish details of their findings today in BMC Biology journal.

Reed is quick to point out that there was no monkey business between
gorillas and humans. Of course gorillas are apes not monkeys, but this
would be a perfect story for Ricky Gervais podcast star Karl Pilkington.
It certainly wouldnt have to be what many people are going to immediately
assume it might have been, and that is sexual intercourse occurring
between humans and gorillas, Reed says, Instead of something sordid, it
could easily have stemmed from an activity that was considerably more
tame.

Reed suggests that 3.3 million years ago, gorilla lice took up residence
in the pubic region in our ancestors, this was probably around the same
time that evolution took us from a fully hirsute state to our current
nakedness. With no hair on our bodies other than the head and pubic
regions, the lice would have been hard pushed to linger anywhere else.

http://www.sciencebase.com/science-blog/people-caught-pubic-lice-from-gorillas.html