Singing satirist Joan Cushing -- better known as Mrs. Foggy Bottom to those who've caught her at the piano of Alexandria's Cafe Lafayette as she cheerfully punctures assorted political balloons -- is leaving the club after 9 1/2 years, and this Friday and Saturday are her last two nights. (She'll be appearing Sunday nights at Cates starting July 6, and meantime has been building a seven-person musical revue around her Mrs. Foggy Bottom persona). Call Cafe Lafayette at 548-0076. THE GREAT INDOORS

Here are some other entertaining (and, in general, air-conditioned) alternatives to consider this weekend:

Friday: Distinctive guitar pop from the Bongos, with the distinctly compatible opening act B-Time, at 9:30 Club. $9. 393-0930.

Friday and Saturday: Singer-actress- comedienne Patricia Englund's affectionate and funny one-woman show, "Songs I Learned at My Mother's Knee & Other Low Joints," at the National Portrait Gallery's Great Hall, via the Smithsonian Resident Associate program. $9 nonmembers. Call 357-3030, and while you have them on the line, might as well ask about next Wednesday night's concert in the Portrait Gallery courtyard by ex-Mountain Laurel singer Laurel Blaydes and local bluegrass-swing mainstays Old Friends.

Saturday: At the tiny Takoma Cafe, some husky, heartfelt, hit-the-sentiment-on-the-head singing and guitar-playing by local songwriter Steve Erwin. $3. 270-2440.

Sunday: An eclectic bargain, at $5, is the Royal Pacific Cultural Exchange open competition -- wherein the prize is an expense-paid trip to the Far East -- among six local musical and five dance groups: the Buck Hill Quartet, the Dance Union, the D.C. Contemporary Dance Theater, the D.C. Youth Ensemble, the Howard University Jazz Ensemble, the K. Shalong Trio, the Lisa Rich Quartet, the Mike Crotty-Deater O'Neill Quintet, Perlo/Bloom & Company, Sweet Honey in the Rock and the Upright Vertebrates. Showtime is 3 p.m. at Duke Ellington School of the Arts; tickets at the door or at Ticketplace (12th and F NW). -- R.P.