P. D. Q.
Pretty damn quick.
This abbreviation for 'pretty damn quick' or 'pretty damned quick' is now so commonplace that it is often written without the full stops, i.e. 'PDQ'. Many abbreviations have origins that are difficult to trace. With PDQ life is a little easier. The term was first used in The Mighty Dollar, a play by Benjamin E. Woolf, first performed in 1875 at New York's Park Theatre. The play's money-hungry character Judge Bardwell Stote habitually used abbreviations like T.T.T - a 'tip-top time' and G.I.C. - 'goose is cooked'.
"That's right, you'd better step P.D.Q., pretty damn quick."
'Pretty damned quick' was already in use by 1875, for example, this piece from the Memoirs of Charles Mathews, Comedian, 1839:
"If he showed me any of it, I'd make him clear out pretty damned quick."
Why P.D.Q. lasted and the numerous other abbreviations from Woolf's work didn't is open to debate.
See other phrases that were coined in the USA.