One who practices butthole surfing - the act of intravenously injecting an aqueous solution of both LSD and heroin (or another interchangably potent opioid analgesic). The author strongly discourages this kind of behavior, being considerably more risky than IV self-administration of either compound independently, which is saying alot.
The name was of course also adopted by the well known Texan acid-punk band the Butthole Surfers.
An example of this kind of a butthole surfer is totally
superfluous by virtue of the self-explanatory nature of the above definition