Of course Nude Raider was a huge rumor, but the one I remember best is the infamous GamePro April Fools joke which claimed you could play as Sheng Long in Super Street Fighter II Turbo. A lot of people, including myself, didn't realize it was a joke. I never tried to do the almost impossible trick, which IIRC involved double-perfecting every computer opponent including Akuma and something else I don't remember, but many other people attempted it.