Green’s Dictionary of Slang

(US campus) someone who is amusing, likeable, eccentric.

1986		Eble Campus Sl. Nov.
1996		Eble Sl. and Sociability 79: Among the slang items that seem to derive their humor from the polysyllabic Latin- and Greek-based elements of the vocabulary are [...] somnambulance ‘someone who is funny, likable, crazy’.