Eddie could have played the balding white man just as easily as Larry. However, this movie isn't all about Eddie. It's also about sex jokes and fart jokes. Dogs hump dogs. Hamsters hump hamsters.
Hamsters hump people.
There's a lot of indiscriminant humping going on in this movie. And there's a lot of farting. Some of the farting saves the world. Some of it tosses goo around the room. Some of it just happens for no reason other than Eddie's love of the fart.