It's "the devil's interval", the harshest pair of notes other than adjacent ones. And, maybe for that reason, early hardcore punk bands latched onto the idea of chord changes, e.g. from C to F#, that moved by a tritone. It's a sound that has become cliché over the years (even finding its way into Danny Elfman's theme for the TV adaptation of Dilbert, that punkrock icon), but still devilishly potent on occasion.