I guess it's short for "변태" meaning "a pervert". :) "변남" = "변태(a pervert) 남자(a guy)" \^o^/

korean is not a language that you can randomly pick a word to ask without context (in most occasions). This is a heavily context-based language. Give us some context maybe you will get an answer.

Im not quite sure but I think 변 means side .-.