"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.

"open wooden vessel made of staves," late 14c., from Middle Low German, Middle Dutch, or Middle Flemish tubbe, of uncertain origin. Related to Old High German zubar "vessel with two handles, wine vessel," German Zuber. Considered to be unrelated to Latin tubus (see tube (n.)); one theory connects it to the root of two based on the number of handles. Also 17c. slang for "pulpit;" hence tub-thumper (1660s) "speaker or preacher who thumps the pulpit for emphasis."

1852 in reference to a modern, large, low-pitched brass musical instrument, from French tuba, from Latin tuba (plural tubae) "straight bronze war trumpet" (as opposed to the crooked bucina), related to tubus (see tube (n.)).

recreational pastime of riding a river on a truck tire inner tube, 1975; see tube (n.).

1670s, "having the form of a tube or pipe," from Latin tubulus "a small pipe" (see tube) + -ar. Teen slang sense attested by 1982, Valspeak, apparently from surfers' use of tube as slang for a hollow, curling wave, ideal for riding (1962).