Friendship between women: A woman didn't come home one night. The next morning she told her husband that she had slept over at a friends house. The man called his wifes 10 best friends. None of them knew anything about it.
Friendship between men: A man didn't come home one night. The next morning he told his wife that he had slept over at a friends house. The woman called her husbands 10 best friends, 8 of which confirmed that he had slept over, and 2 said that he was still there.