Yes, Eminem shows up in Happy Gilmore 2. He plays the famous heckler's son from the first movie, whose part was played by Joe Flaherty. As part of his role, Eminem makes fun of Happy on the golf course by calling him a "jackass," just like Happy's dad did in the movie.

The ones who didn’t count are the ones that have full-on roles, e.g., Bad Bunny, Haley Joel Osment, and Benny Safdie. Also, anyone who was in the first film doesn’t count as a celebrity cameo (though, thankfully, just about everybody who could come back did come back).