Yippee!
2d Red-light - extract from OED...
Red-light To force (a thief, tramp, etc.) out of a moving train (see quot. 1931). Hence fig., to discharge or expel; to dispose of, kill. U.S. slang (orig. Circus)
"1931 G. IRWIN Amer. Tramp & Underworld Slang 156 Red light, to do away with. The term originated with the..custom of disposing of an undesirable member of a circus or carnival crew by taking him out on a train platform after dark and hurling him off the train... A red light is a danger signal in any case, and on a railroad indicates a full stop."