County fairs aren't just for kids, you know. In fact, you might run into some rabbits, sheep, cattle, even a horse or two.

For this year's free Fairfax County 4-H fair, organizers have planned a weekend packed with everything from horse shows, sheep and beef judging, arts and crafts to music and an auction where you can bid on a five-day trip to Reno, Nevada. It all happens at Frying Pan Park in Herndon from 8 to 7 on Saturday and 8 to 5 on Sunday. Blacksmiths will pound their anvils; the Fairfax County Extension Homemakers will sell homemade baked goods, corn-on-the-cob, popcorn, cotton candy and other old-fashioned fair goodies; and both days at noon, the celebrity auction gets under way near the park's outdoor horse ring. Items to be sold include: autographed photos of Richard Nixon, astronaut Sally Ride, the Statler Brothers and Senator John Glenn; dinners, magazine subscriptions, weekend trips and gift certificates. And don't bother bringing dinner on Saturday because from noon to 6 you can help yourself to barbecued chicken served with tomatoes, salads and rolls for $3. That night at 7 local bands and quartets will add a special country-music sound to round out the day.

Sunday's agenda includes a pet show at 2 and continuous free entertainment throughout the afternoon. To get to Frying Pan Park, take I-66 to U.S. 50 west, exit at Chantilly, turn right onto Centreville Road (Route 28), then turn right at West Ox Road and follow the signs. Call 691-3400; free.

And over the river in Oxon Hill, there's going to be a humdinger of a hoe-down at the Oxon Hill Farm on Sunday from noon to 5. The snappy sounds of country-swing, ragtime and gospel music will highlight the hoopla as performed by "Bowling Green" John Cephas, "Harmonica" Phil Wiggins, Eleanor Ellis, John Jackson, Flora Molton, Larry Wise and Roy Dunn. To get there, take the Beltway to exit 3A and turn right on Oxon Hill Road. Call 839-1176; free.