1.A term used to describe a poor joke most often in a sarcastic response to being the comic's intended target. 2. A dry response to a person who is witty and clever only to themselves, usually said to the person with a completely straight face.
Steve: I just flew in for the holidays and boy are my arms tired!
Joe: Yeah Steve that was haha-larious, you should quit your job as an architect and totally do stand up.