The phrase boob tube is slang for two very different things:

• In British slang, a boob tube is a woman's tight skimpy strapless and shoulderless (thus "tube") top, usually made of an elastic material. It is held up by the breasts, thus "boob", as boobs is slang for a woman's breasts.

• In American and Canadian slang, a boob tube is a television, normally with a negative or humorous connotation. This usage derives from the definition of boob as a stupid or foolish person, plus "tube", from the television's cathode ray tube.