A blackout gag is a term mainly used in broad, rapid-fire, slapstick comedy to describe a manner in which a gag or joke is executed. The term is derived from burlesque and vaudeville, when the lights were quickly turned off after the punchline of a joke to accentuate it and/or allow for audience laughter. It may use a shock value to define the joke, and may not be initially noticeable to all viewers if it is a very fast joke.