A man’s wife doesn’t come home one night.
The next morning, the wife tells her husband that she had slept over at a friends house. The husband then contacted all of his wife’s friends asking about it: none of them said that she was staying the night.
A few nights later, the husband doesn’t come home one night. Just like his wife, the next morning he tells her that he had slept over at a friends place. His wife then contacted all of the husbands friends to ask about: and apparently the husband was at 8 houses, 2 of which said he was still there!