put on the red light(redirected from a red light)
put on the red light
slang To make it known that one engages in prostitution. Refers to the use of red lamps to show that an establishment is a brothel. A: "Tom's new girlfriend used to put on the red light—if you know what I mean." B: "Whoa! Does he know that?"
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.