tube n.

"television set," U.S. slang, 1959, from boob "stupid person" + slang tube (n.) "television, television programming;" the original sets had vacuum tubes in them. It seems to have been popularized, if not coined, by William Ewald, television columnist for the UPI news wire, in a column resigning his position, which was widely reprinted in US newspapers in August, who headlined it variously.

To all those who say TV provides the sort of fare that they, ordinary people, like, I say shame on you for reveling in your ordinariness.

To all those who say there is room for all kinds of tastes, nonsense again. There is obviously a hierarchy of values in life—without it, we become vegetables. If you prefer to squander your free time on Lawrence Welk, The Texan, The Price Is Right and other drivel, it may be time for you to question your values. ['Sorehead' Calls It Quits As Boob Tube Chronicler," Tucson Daily Sun, Aug. 14, 1959]

1809, from test (n.) + tube (n.). So called because it originally was used to test the properties of liquids. Test-tube baby is recorded from 1935.