Friendship among women:
A woman doesn't come home one night. The next day she tells her
husband she slept over at a friend's house. The man calls his wife's
10 best friends. None of them knows about it.
Friendship among men:
A man doesn't come home one night. The next day he tells his wife he
slept over at a friend's house. The woman calls her husband's 10 best
friends. Eight of them say he did sleep over, and the other two claim
he's still there.