"when someone tells a joke, a one-liner, on stage, the drummer often hits his tomtom"
But that is never baboom. It is always ba-dum BUMP or ba-dum CHING.
In some live comedy shows, a drummer is usedto indicate the punchline of a joke- you'll sometimes see people writing rimshot after a joke to imitate this. It is often associated with weaker jokes that require some help to make the audience laugh IMO. Someone suggested that baboom might refer to this.WHAT?
In the UK, we do use boom boom, because of the puppet fox Basil Brush.But that is never baboom.
Certainly badaboom, also badaboom-badabing, have been around forever. So badump, or baboom, or anything like it, could be used as an accent in live shows. The drummer hits the rimshot, or the highhat, or whatever, at the same time. Wonder if there's a word for doing that?
Otherwise, baboom is not a real word that I know, although it could appear as a comic book explosion sound.
Boom Boom... suggests 'out go the lights'. from the blues hit song, never heard of Mr. Brush.