I already read it in new scientist
It's because it helps to grip cocks better when they're wet.
( 2 Can Chunder Word to your mums, I came to prod bums, Thu 10 Jan 2013, 22:09, archived)

They evolved so we could masturbate better in the bath

( 2 Can Chunder Word to your mums, I came to prod bums, Thu 10 Jan 2013, 22:10, archived)

if we'd evolved to wank in the bath, we'd have evolved to have no body hair at all

( glued eel /questions/questionsyoudliketoask/post1648081, Thu 10 Jan 2013, 22:26, archived)

Like manatees?
Do you think manatees evolved to wank in the bath?
( 2 Can Chunder Word to your mums, I came to prod bums, Thu 10 Jan 2013, 22:32, archived)