Green’s Dictionary of Slang

(US campus) someone unusual, crazy or stupid.

1964		in Current Sl. (1967) I:4.
1974		Eble Campus Sl. Mar. 6: twink – a person who is dumb, unusual, or slightly crazy.
1989		H. Rawson Dict. of Invective (1991) 397: twink [...] a weird person.
1996		Eble Sl. and Sociability 59: Derogatory epithets abound, for example [...] tang, three dollar bill, tool, twerp, twink.