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?"
Fogey/fogy /fougi/ sl. (early 18C+, orig. Scot) old-fashioned, stuck-in-the mud.
Person with old fashioned ideas which he is unwilling to change: Come to the disco and stop being such an old fogey!
You think me an old fogeyand an old tory, his thoughtful voice said. I saw three generations since O’Connel’s time. I remember the famine. Do you know that the orange lodges agitated for repeal of the union twenty years before O’Connel did or before the prelates of your communion denounced him as a demagogue? You fenians forget some things. (James Joyce, Ulysses. PenguinBooks,1992. p. 38)