Tell him I was too fucking busy — or vice versa.

Dorothy Parker (1893-1967) American writer

(Attributed)

In Hard Times, Vol. 6 (1967), the anecdote is that a messenger pounded on her door for several minutes, having been sent by a New Yorker editor for some promised writing. She finally opened a second-floor window, called down to find out what was the matter, and provided this retort.

In Oscar Levant, The Unimportance of Being Oscar (1968), it's phrased "Too fucking busy, and vice versa."