You don't often see cartoon characters get implants but that's exactly what I suspect is going on here. But what kind of implants are we dealing with? Those are not your garden variety big fake boobs. (What kind of expression is "garden variety?" I know WHEN to use it but I never really bothered to research the etymology.) Arsen thinks they're made of jello, I say it's some kind of custard pie filling. What say you, precious reader?

Another theory I just came up with is the animator was bored. Other than the breasts there isn’t much going on in this scene. It’s gratuitous and unnecessary so maybe they just put that in as an afterthought?