Tube Electronic valve. Now an almost totally historic term, of course. Also vacuum tube. Tubing Floating down a river with the aid of an inflated inner tyre. You occasionally see roadside establishments hiring tyres for tubing and organising transport to or from the starting or finishing place.
Tubing can be dangerous.
Turnpike Toll road. TVA Tennessee Valley Authority - the body responsible for the administration of the numerous dams on the Tennessee River and its tributaries. A slang expression meaning 25 cents. You never hear of any number of bits other than two.