Green’s Dictionary of Slang

(US campus) a fool, an idiot.

1974		Eble Campus Sl. Mar. 2: Richard Nixon is a flaming dosc.
1996		Eble Sl. and Sociability 78: The foreignness of the sound seems to be a large part of the appeal of borrowing in slang. Mock Latin doscus and its clipped derivatives dosc and dosh mean ‘fool’.