Contrary to popular belief, black acid is not an acid/pcp combo, but a type of very, very dirty LSD crystal. The crystal is black, hence the name. The "family" name for this crystal is champagne. Really nasty stuff. The reason for this myth is that the effects of all the impurities alter the trip so much that it's almost like PCP.
You have any of that black acid man? Nastiest shit ever!