Friendship
Friendship among women:
A woman doesn't come home at night. The next day she tells her husband that she slept over at a friend's house. The man calls his wife's 10 best friends. None of them know about it.
Friendship among men:
A man doesn't come home at night. The next day he tells his wife that he slept over at a friend's house. The woman calls her husbands 10 best friends. Eight of them say he did sleep over and 2 claim he's still there.