Baltimore's Showcase of Nations continues with the Afro-American Afram '87: A Salute to the Black Athlete," a weekend-long event that starts at 7 Friday with a parade of more than 1,200 marchers. Activities noon to 10 Saturday and Sunday include a double-dutch jump-rope contest at noon Saturday, magician Bill Gross at 3 Saturday and a 10K race at 7:30 a.m. Sunday. On the musical agenda, soul/pop singer Regina Bell performs at 8:30 Friday, R&B group Surface at 7 Sunday and pop singer Deniece Williams at 8:30 Sunday. It's all at Festival Hall, Pratt and Sharpe streets; admission is $2 per day. Call 301/837-INFO.


Shake the summer blues by shaking your body instead, at Kramer Books and Afterwords Cafe's ninth annual "Dancin' in the Street" block party 2 to 8 Sunday on 19th Street between Dupont Circle and Q NW. Local blues ensemble the Assassins and rock 'n' rollers Goin', Goin', Gone will provide the tunes. If it rains, the party's still on; the name just changes to "Dancin' in the Rain." Call 387-1462.

The Dance Place is the place to hop beginning at 8:30 Friday when Steve Bloom and Crux play ancient traditional rhythms and new music. After the concert, everyone is invited to dance to taped African juju music. Admission is $5 and $7 at the doors at 3225 Eighth St. NE near Brookland station on Metro's Red Line. Call 269-1600.

If you're more interested in watching than moving, two New York-based dance groups are performing at the Capitol Hill Arts Workshop. The two avant-garde groups, Phffft and the Tennessee Project, will perform at 8 Friday at the center, at Seventh and G streets SE. Admission is by donation. Call 998-5489.


The Fairfax County 4-H Fair is 8 to 5 Saturday and Sunday and free at Frying Pan Park, 2705 West Ox Rd. in Herndon, with animal shows, crafts, games and a barbequed chicken dinner. 691-3400 . . . the seventh annual Friendsville Summer Festival is noon to 11 Saturday with everything from a parade to a talent show to fireworks in Friendsville, off U.S. 48 in Garrett County. Free. 301/334-1948 . . . the Slavonic-American Day Festival is 12 to 7 Sunday at St. Gregory Parish at 12420 Old Gunpowder Rd.in Beltsville. Free. 953-9323 or 439-5737 . . . Oxon Hill Farm's 20th anniversary celebration is noon to 4 Saturday with games, contests and bluegrass music. Free. 839-1177 . . . Free concerts in the area include Kaleidoscope performing light jazz at 7 Saturday at Fort Hunt Park, five miles south of Alexandria on the George Washington Parkway. 485-PARK . . . a day of Dixieland with Stevie and the Sheiks, the King Cotton Jazz Band, the Last Chance Jazz Band and lots of others noon to 5 Saturday at the Village in Shirlington, Randolph and South 28th streets. Call 739-2900 . . . Ragtime pianist Harvey Jacobson at Arlington's Lubber Run Amphitheater at 8 Friday. 558-2165 . . . the U.S. Air Force Airmen of Note jazz ensemble at the Sylvan Theater at 8 Friday. 767-5658 . . . Hot Jazz on the steps of the Old Courthouse Building in Leesburg, at 7 Sunday. $2. 703/ 777-0574 . . . the D.C. Youth Orchestra and soloist Fred Irby at 7 Friday at the Calvin Coolidge High School at Fifth and Tuckerman NW. $2.50 for adults, $1.25 for students and seniors. 723-1612.


It's time for a whole lot o' country 10 till 6 Sunday at the WMZQ Bull Run Country Jamboree. There'll be games and contests that include corn-on-the-cob eating, log-sawing and watermelon-seed spitting, plus dancing with the Foggy Bottom Cloggers. Between 12:30 and 5, there'll be real foot-stomping stuff by Pinkard and Bowden at 12:30, Pake McEntire at 12:45, Ronnie McDowell at 2, Sawyer Brown at 3:15 and the Judds at 4:30. Take the Centreville exit off I-66 and follow the signs. Tickets are $15 at the gates. Call 352-5908 for information.


If you want to set the clock way back, check out the Great Medieval Lammastide Fair, 11 to 6 Saturday and noon to 6 Sunday at Berrywine Plantations in Mt. Airy, just north of New Market, Maryland. Beside a replica of a ninth-century Viking ship and battle reenactments, there'll be demonstrations of 10th- to 13th-century crafts, including stonecarving by a cadre from the National Cathedral. It's $2 per car and $2 for a tour of the wineries. 301/662-8687.


Have a swell time over at the 13th annual Jug Bay Raft Regatta, noon to 4 Saturday. Any group or individual can enter a homemade or custom-made raft in categories that include speed, creativity and overall performance. The race is at Jackson's Landing on the Patuxent River at Jug Bay Natural Area. Registration is 8 to 11 Saturday and it's free. Call 627-6074 for information.


It's an equine kind of weekend at the following events:

The Potomac Morgan Horse Club presents the Freestate Morgan Show at the Prince George's Equestrian Center 8 to 5 and 7 to 10 Friday and Saturday. More than 200 horses will compete in the show at the center, on Rte. 4 in Upper Marlboro. Free. Call 952-4740.

Dominion Saddlery's 12th annual summer tent sale is 10 to 5 Saturday and Sunday with five tents full of all the tack and horse gear you'll need. It's on the grounds of the saddlery's store on U.S. 50 eight miles west of Fair Oaks Mall. Call 471-4329.