Green’s Dictionary of Slang

old-fashioned, socially inept, dull, foolish.

1982		Dly Record (Morristown, NJ) 28 Oct. 25/4: I know she thinks this guy is strictly melvin [...] she has me make up an excuse to him that [...] she can’t come to the phone, you know?
1992		Simpsons [TV script] Some say to love your country is old-fashioned — uncool — melvin [HDAS].