Definitions by the mengine

Gaydar 

A make-believe radar that is within the human mind. It is used to detect gay men. It is NOT, however, something that a gay man uses to detect other men, gay or not.

Person A(who is gay): Dude, how did you find me in this mall?
Person B: You showed up on my gaydar.

Gaydar by the mengine December 4, 2012