Someone's ability to sense if someone is gay or not when it's not obvious.

A Bloomer is someone with a bright outlook on life who is optimistic in nature. Bloomer's frolic in every opportunity to be happy and try to make the most out of life. The opposite of a Bloomer is a Doomer. The term Bloomer originated specifically as a counter to the Doomer on sites especially like 4Chan.

The ability/gift of being able to detect homosexuality in other people.

the ability to sense--without being told and without obvious visual clues--that someone is gay.

A sense that allows for someone to detect homosexuality in another

Extra sensory perception that allows one to immediatey know who is a homosexual.
Origin: The combination of the words "gay" and "radar".

The gift of being able to sense the homosexual vibe.

Extended form : Gay Radar