Friendship among Women:

A woman didn't come home one night. The next morning she told her husband that she had slept over at a friend's house. The man called his wife's 10 best friends. None of them knew anything about it.

Friendship among Men:

A man didn't come home one night. The next morning he told his wife that he had slept over at a friend's house. The woman called her husband's 10 best friends. Eight confirmed that he had slept over, and two said he was still there.