The OED offers two verbs; to loo, meaning to subject to a forfeit in the game of loo, and to loo, meaning to shout “halloo”, to urge on by shouts. The second sense is said to be obsolete and the last citation is from 1711.
There is also a verb, to lew, meaning to make warm, to become warm or to shelter, and “loo” is offered as an alternative spelling. This, too, is said to be obsolete.
I guess that could have taken place in “Sanctuary,” an '80s disco in a former NYC church . . . not the place in which I looed (stood in the queue for the loo) with Truman Capote.
Loo is a Chinese word for boil, I believe. Somewhere I have a recipe (in English) for “looed chicken,” chicken boiled in a flavorful sauce. So yes, I have looed, and I’m not ashamed to admit it.