Omg. That's what the bubumche means. I never got that. No one ever explained. Hahaha. Genuinely thought it meant "that's the punch line", amazing. I'm halfway through life and still catching up. I am definitely more into the pointless style joke posted by OP.
Clearly it is, but I'd missed anything about it being the sound of 2 people managing into something and perhaps it landing on the floor.