Green’s Dictionary of Slang

1. (also bubble, bubbletop) the flashing light(s) on top of a police car.

1966–8		in DARE.
1972		B. Rodgers Queens’ Vernacular 126: The revolving red lights are the bubble gum machines.
1986		S. King It (1987) 935: He peeked at the car. Not a fuzzmobile: no bubbles on the roof.
1991		P. Blauner Slow Motion Riot 186: Riot cops shove their way down the middle of the street as people scream and bubble gum lights sweep over the building.

2. the vehicle itself.

1975		L. Dills CB Slanguage 18: Bubblegum machine: vehicle with flashing lights, usually a police car.
1980		Eble Campus Sl. Spring 1: bubble gum machine – police car.

3. (US gay) a condom vending machine, as found in a men’s public lavatory.

1972

B. Rodgers Queens’ Vernacular 37: bubble-gum machine (obs) a condom-vending machine found inside men’s lavatories.