Definitiongay + radar to describe the intuitive ability or sixth-sense in some people to recognize gay people.
Quote: Geneva Overholser. McCain's Straight Talk, in The Washington Post (January 24, 2000): ' In other words, McCain said - in answer to a dumb question - that we can sometimes tell when people are gay. He didn't snarl epithets. He didn't snicker about limp-wristed men. He just said that sometimes you can tell. This is so commonly understood to be true that there is a slang word for it: "gaydar" (gay radar).'