sight gag

In comedy, a visual gag or sight gag is anything which conveys its humor visually, often without words being used at all.There are numerous examples in cinema history of directors who based most of the humour in their films on visual gags, even to the point of using no or minimal dialogue. The first known use of a visual gag was in the Lumière brothers' 1895 short, L'Arroseur Arrosé ("The Waterer Watered"), in which a gardener watering his plants becomes the subject of a boy's prank.
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Noun
1. a joke whose effect is achieved by visual means rather than by speech (as in a movie)
(synonym) visual joke
(hypernym) joke, gag, laugh, jest, jape