one-liner 
noun informal
A short joke or witty remark.Some people start with a one-liner or a joke, I personally like short stories that in a simple way say something about the speaker, or the topic, or sometimes both at the same time....
- Not just bytes, she is besotted by witty one-liners and mushy expressions, phrases.
- There is a smooth flow of jokes, some nice one-liners, the sort to send the masses giggling away.