Ok, this would have been in like 2004-5 or so. I had some disk for gamecube with a set of bonus features including trailers, and there was one for WarioWorld, and I remember clearly hearing him say "what the fuck?" at one point in it. I can't find the disk anywhere or any evidence of it on youtube, and no evidence that the vulgar line was part of the main game. I think it might have been some Zelda collector's edition disk, if that helps.