I think they are implying that Jimmy was the "original party animal" like Slurms. Either that or it's how they "look similar" in this photo due to the Hawaiian shirt.
Also, if you look closely you can see a little green sludge coming out of him. And just like on TV, it tastes delicious.
Before anyone mentions, I know it wasn't slurms who made the sludge. Just the first awful thought that came to mind, and I felt like commenting it, so there.
You can't believe people would break into song as a rock star dog pulls up in a bullhorn car, right before he plays the drums? Man, you're a hard one to fool!