A non-joke or an anti-joke is a joke with a setup but no punchline. It sets your expectations for something funny and gives no pay off, thereby somehow being funny anyway. I could have sworn there was a thread for this before...
For example: What leaves a bigger memory than a passionate kiss?
Sorry but you are not allowed to view spoiler contents.
What did Batman say to Robin before they got in the car?
Sorry but you are not allowed to view spoiler contents.
How do you confuse a blonde?
Sorry but you are not allowed to view spoiler contents.
What do you call a fish with no eyes?
Sorry but you are not allowed to view spoiler contents.