I noticed that Sean was wearing what appeared to be M-frames the first time I saw this movie, but just recently I watched it again on HBO and realized, as brian pointed out, they are Fakes.
if you pause the movie on DVD and look closely. They are not real M-Frames, they are fakes.
LUSCIOUS -
... also, you may have notice Adam Sandler with the Smoke sandals on. I believe he even wears a couple of different colors in the film.