Legend has it, at the ultra-competitive Juilliard of the 1950's, pianists would hide razor blades in between the keys of the practice room pianos, to cut up their rivals fingers. I don't think it is actually true.
Charles Rosen tells a story (which now I can't find in my books) about two students sitting in the front row of one of his concerts, I believe it was the Brahms second concerto; right before a particularly difficult passage, he heard one of them say, "Watch this," to his friend, and of course screwed the whole thing up.
Walter Ramsey