Green’s Dictionary of Slang

1. (US black) a young middle-class white person [stereotyping].

1967

R. Conot Rivers of Blood 227: But the Surfers, especially, nobody I hate worse or'd rather fight than the Surfers!1 1Surfers is a generic name for middle-class kids.

2. (drugs) phencyclidine [? one surfs inner space].

1979		H. Feldman et al. Angel Dust 124: The large number of street names it has been accorded over the years: [...] surfer.
2001		ONDCP Street Terms 20: Surfer — PCP.