1.A word that is used to describe something of humor. Uses a similar idea from the movie, "Dickie Roberts" (starring David Spade), whose catchphrase was "That's Nuckin Futs!".
2.A somewhat sarcastic response to a relatively inhumorous situation.
Everyone was falling off the pews with laughter when Pastor Dave slipped and said Milla was Charles's "new ride" instead of "new bride." It was so fularious, Grandma!
A 'better' alternative to using the word 'crazy' or 'insane' to someone. Or just a fun way to call someone crazy. Also, 'mentally jolly' can be used. From the Family Guy episode 'The Fat Guy Strangler'.
"Dr, is my brother really insane?"
"Mrs Griffin, we don't use the word 'insane', we prefer the term 'mentally hilarious'"