WordNet
n. someone who takes LSD
Wikipedia
"Acid Head" is a song recorded by the American garage rock band the Velvet Illusions. It first appeared as the A-side to the group's debut single, which was released on Tell International Records in mid-1966 (see 1966 in music). The writing of the composition is credited to keyboardist Steve Weed and the group's manager George Radford, however, it is reported that "Acid Head" actually originated from an outside composer. At the time of its first release, the tune suffered from limited radio-play time. Over time, "Acid Head" has since become recognized as a garage rock classic and is widely accessible on multiple compilation albums.
Usage examples of "acid head".
And he said then it would be pretty clear to everybody that I was making it up just to try to get him in trouble for doing his job and nobody would believe it because nobody ever believes an acid head about anything, and those pictures would make a hog sick.