Those Crazy Geniuses

Just when you thought you'd seen it all, the 14th Annual Inventors Expo comes along to show off some of man's most recent patented breakthroughs: A relief station for cats, a folding cello, an electronic page turner and a retractable fish net, to name a few. The United States Department of Commerce sponsors this free exhibition Saturday from 1 to 5, Sunday 10 to 5, at the Patent and Trademark Office, Public Search Room, Crystal Plaza Building 3, 2021 Jefferson Davis Highway, Arlington. 557- 3341. Roaring Into the New Year

It's the Year of the Tiger, so you'd better make tracks to the Chinese New Year celebration in downtown Washington this Sunday. The festivities, designed to celebrate bravery and ward off evil spirits in the coming year, kick off at 1 with a parade of bands, a 30-foot dragon and lion dancers; 10,000 rounds of firecrackers will sound off, too. The half-hour parade begins at Ninth and H streets in Washington's Chinatown and winds up 10 blocks later at an open-air stage where there'll be kung fu demonstrations, folkdancing and Chinese music. The stage is on H Street between Sixth and Seventh streets; it's all free. By Metrorail, exit from the Gallery Place station on the Red/Yellow lines. 638-1041. Mardis Gras Groovin'

You can mask your reckless abandon this weekend at several Mardis Gras and Carnival celebrations. Here are your excuses to cut loose:

* The Torpedo Factory Art Center goes whole hog Saturday from 8 to 1, when it opens up all three floors for Mardi Gras revelry. Zydeco band Loup Garou (bayou talk for "crazy werewolf") provides Cajun dancing music. But if you've got two left feet, you can still hide behind an outrageous costume, eat red beans and rice or watch a magician. Prizes will be awarded for best costume. Tickets are $8 in advance; $11 at the door. The Torpedo Factory is at 105 N. Union Street, Old Town, Alexandria. 838- 4565 between 10 and 5.

* If you're searching for sambas, the D.C. Partners of Brazilia are holding their 12th Annual Brazilian Carnival this Saturday evening from 8:30 to 2 in the Regency Ballroom of the Shoreham Hotel, 2500 Calvert Street NW. There'll be prizes for the best costume, and non-stop music from Edouardo Prates and his 15-piece samba band. Tickets are $30 each and available at the door; admission includes three drinks and snacks. 966-3338.

* Baltimore's Italian community celebrates its 6th Annual Carnevale Friday, noon to 10, Saturday and Sunday, 10 to 10, at Festival Hall, Pratt and Sharp streets (across from the Convention Center). There'll be all kinds of Italian food, music and dancing. $1 tickets are available at the door and good all three days. 301/837-6500. Black History Revisited

Black History Month shifts into high gear this weekend:

* There'll be a free two-day rhythm and blues symposium at the Museum of American History, 14th Street and Constitution Avenue NW. It begins Friday at 7 p.m. with a panel discussion on blacks in radio; a concert featuring saxophonist Paul (Hucklebuck) Williams follows. Saturday beginning at 9:30 a.m., several discussion groups will survey the evolution of R&B until 3:30. Then at 8 p.m., there'll be a concert featuring the Spaniels and the Orioles, considered one of the first R&B vocal groups. All events are in either the museum's Carmichael Auditorium or Flag Hall. Call 357-4176 to pre-register.

* The Alexandria Association for the Preservation of Black Heritage sponsors free guided walking tours of historic homes, churches and other black landmarks in Old Town this Saturday at 1 and 2:30. Meet at the Lyceum Center for Alexandria Heritage, 201 South Washington Street; a slide show precedes each tour. Reservations are necessary. 838-4994.

* The Museum of African Art is presenting "Myth in Black Africa," a program of music, slides and discussion of African folklore Saturday from 2 to 3. The museum is at 318 A Street NE. 357-2700.

* Journey through the history of black music with "Black Reflections," a free multi- media performance Saturday night at 8. The Ambassadors Orchestra plays spirituals, ragtime, jazz, blues, and rhythm and blues for the program, which also includes dance and slides. The performance is at the Takoma Theater, Fourth and Butternut streets NW. By Metrorail, exit from the Takoma station on the Red line. Seating is free and on a first-come basis. 673-7663.

Celtic Salute

Some of Ireland's top folk musicians hit town to set you reelin' in a Folklore Society of Greater Washington concert this Sunday at 4. Joining guitarist Jackie O'Beirne will be members of Planxty, De Danaan and the Bothy Band; the concert is at Gaston Hall, on the Georgetown campus. Tickets at the door are $8; $6 for FSGW members. 281-2228. The Killer Bee

If you enjoy watching people who think they're smart get stung a little bit, the Trivia Bee III's for you. At 8 this Saturday, 50 contestants will face a firing line of general trivia questions at Gunston Arts Center, 2700 South Lang Street, Arlington. Last year's stumpers included: "What is the only bird to nest in all 50 states?" and "Hitler, Mussolini and FDR all died in what month of 1945?" Tickets are $3 for adults; $2 for students and seniors. 739-2921. (Oh yeah, just in case the answers have slipped your mind: The bird is the mourning dove, the month was April.)