Washington has its Mark Russell and its Art Buchwald, but it also has, thankfully, its Joan Cushing, whose nearly one-woman show of sometimes light-hearted, sometimes trenchant social and political satire packed the Trinity Theater last night.

Perched cross-legged on a high stool as Mrs. Foggy Bottom, Cushing looked down her pince-nez as she dropped names of acquaintances (Ronald Reagan, Elizabeth Taylor) or sang of her exclusive shopping habits ("I buy designer chickens by Frank Perdue").

Seated at the grand piano she plucked materials from her own songbook, offering witty commentary on Walter Mondale, Gary Hart, Edwin Meese, Marilyn Monroe, unemployed actors and, in a number titled "Sleaze, Sleaze, Sleaze," the need for "a female Abscam" and "male secretaries who cannot type."

Rhinestone spectacles and a persimmon mouth help perfect the role of a cynical secretary and double entendre enlivened her recommendation of Hechinger's as a happy hunting ground for pick-ups ("There's a lot of studs among the two-by-fours.")

Several cameo appearances by Reagan look-alike, sound-alike and move-alike Don Williams were tapped with the musical apologia, "I'm Not What I'm Not" ("I'd stay the course if I had one").