Grafitti artist 'Banky' managed to sneak his works into several of New York's most famous museums, claiming he could do just as well as the artists exhibited: Wooster Collective on Banksy's stunt (with photos of the works).
I love stuff like this. Not only is it fun when stuffy institutions are stirred up, but it's great fun when it's done in a constructive way.
The most memorable quote, however, is this single sign of modesty (from this article on Banksy's interview w/NY Times):
I wanted to do the Guggenheim but there weren't enough paintings in it, I would have had to appear between two Picasso's and I'm not good enough to get away with that.
But he could get away with putting a painting of an Admiral with a spraycan and anti-war slogans in the background up for several days before being discovered...
Maybe he does have a point about the selection processes for these museums.