"Bolt” was old New York City restaurant slang for “pudding,” and “O.K. bolt” meant “tapioca pudding.” The terms were cited in an 1888 newspaper, reporting on the strange orders at a restaurant on Ann Street.
It is not known how widespread the “bolt” slang term was for “pudding,” and the reason for the name is unknown as well. Other “bolt” citations have not been found.
Hudson River Valley Heritage Historical Newspapers (NY)
24 March 1888, The Rockland County Journal (NY), “Waiters’ Queer Orders,” pg. 6, col. 1:
A NEWS reporter went into a restaurant on Ann street yesterday and after having given his order to the waiter asked him what was the meaning of the jargon waiters usually shriek at the cook.
With a disdainful look at the latter’s ignorance the waiter made answer:
“‘O.K. Bolt’ is another way of saying ‘tapioca pudding.’ All puddings are called ‘bolts’ by waiters.”
-- N. Y. News.