It's an onomatopeia for a drum technique normally accompanying the conclusion of a cheesy joke or a comedy pratfall (where someone is made to look like an idiot by their own devising - such as falling on a banana skin they earlier discarded). It consists of two fast rimshots and a splash cymbal - producing the sound "badum tish".
#1: What does bees do if they don't want to drive?
#2: Dunno
#1: Wait at the buzz stop! Haha!
#2: Badum tish!
The onomatopoeic expression of a drum roll used when a drum kit is not readily available, or the user isn't musically inclined. More often than not to indicate or emphasise a pun or joke.
"What path does a crazy person take through the forest?"
"I don't know Rosie, what path does a crazy person take through the forest?"
Boys who enjoy yaoi (a genre in Japan that contains sexual and/or romantic relations between two men); literally translates to "rotten boy"; corresponding female : fujoshi
May I have an order of regular degular buttermilk pancakes? Without all the added jazz? Hold the blueberry smiley face, strawberry glaze, chocolate chips and whipped cream.