I would like to give anyone out there who doesn't know about it a quick heads up on one of my favorite little systems ... its great for one shot supers games (if you want zany/campy hilarity) its called STUPER POWERS DELUXE. I haven't played for years but it "is a role-playing game in which you play a superhero endowed with silly, useless, and downright gross superpowers, sent into battle against the only slightly less ridiculous forces of evil." You end up with characters who can project smells into the minds of their foes ... catch is they themselves have to experience the smell (have fun with that one), they shoot ice cream (instead of fire or ice or energy beams), heroes summon vehicles made of fruit, etc. crazy retro camp at its finest. This system really isn't the game a group would probably pick for long term play but for some funny one and two shot games this is just a priceless system. Every game I've experienced of it has been a blast.
The hilarious Taco Bell advertisement just screams for conversion into a stupor powers game ... of course the group would have to make a run for the boarder at some point during the session :)