Is it ensure, insure, or assure?
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' slang for a hollow, curling wave, ideal for riding.
Rejected; dead in the water, kaput: Looks like your idea is Tubesville
[1980s+; fr down the tube]