Named for a frequent note in Marx Brothers scripts, this trope refers to space deliberately left in otherwise scripted media to allow for the wacky whims of an actor best known for his improvisations. The crew knows that a particular actor will be funnier if left to his own devices than anything the scriptwriter could possibly come up with. As such, this is possibly the highest compliment that can ever be paid to a comedian, when the writers know that no matter what he or she does, it will have everyone who sees/hears it in stitches. Examples: