When a man decides he wants to shit all over prissy and bitchy attitudes of "real men" and decides to highlight his hair any color he wants. The colors vary and so does the level of highlighted hair, it's decoration that some people enjoy and others don't.
Guy 1: Bruh, you see that freak with the guylights?
Guy 2: Who the fuck cares, don't be a prissy bitch 'bout someone else's decisions that don't personally effect you.
Guy 1: bruh ... but... mah masculinity?
Guy 2: Doesn't exist.
Highlights in a man's hair that is wholly unattractive: generally an indicator of one's toolish nature. Look for a pompous air and cheesy smile. Guylights are perhaps a descendant of the late 90s tendency to bleach one's hair until it looked like a skunk had pissed on it.
When someone try’s to infer you are gay even after you have told them you are not. A form of teasing where a friend might constantly imply you are gay for what you do.
Heterosexual Friend 1: Hey did you see the Oscars last night?
Gaylighting Friend 2: No, I’m not gay.
Heterosexual Friend 1: I don’t think that woman is attractive.
Gaylighting Friend 2: That is because you guys are wired differently.