I'm gonna go there (although you question is quite odd) and the Pokemon Crystal where the sprites are naked, kupo.
a whole bunch of hacked GB-Games are here on Romu. But humourous ones? don`t Know. If you find any: let us now. in a topic maybe. w-what? naked Pokemons? awwwwwwwhhh, I DON`T wanna see Pikachu in this state!!!!
It took me awhile to find one (cant find original) heres a "mature player" patch called "cokemon" http://www.zophar.net/hacks/gb/pokemon-gold-edition/cokemon.html (you have to patch on the clean rom, kupo)
guess, kupo. Post Merge: [time]1254541238[/time] because the storyline somewhat revolves around a coca cola bottle