From the Spanish slang word fundillo, which means "butt." In this case fundillona is a girl with a big booty. Sometimes said jundillona (hoon-dee-yona) especially in Colombia.
Oye fundillona, estás bien rica déjame romperese bomper.
A Rodney Dangerfieldism for a hot tub meaning "rich people farting under water"
According to Rodney Dangerfield, Rich people invented the fonzaloon, after a lavish dinner party sitting together in a warm pool and farting under water