Washington has a new airline: It's called Vice Presidential. Its motto -- "We're not your first choice, but our name's on the ticket."

Such is the fare currently being served up in "Roast of the Town," Hexagon's 31st annual musical comedy revue that raises money for a different charity each year. Among those getting basted in this year's edition are Lee Iacocca, Tipper Gore, Mitch Snyder, Joe Theismann, Cathy Lee Crosby, Tip O'Neill, Mikhail Gorbachev, Gramm-Rudman-Hollings and everyone's perennial favorite -- Richard Nixon.

Due to a bizarre allergy to New Coke, the former president has turned into the Reagans' first dog, Tricky -- a dog with a ski-jump nose, a shifty glance and a 5 o'clock shadow.

"He can do anything except play checkers," President Reagan remarks to the first lady. To which Tricky injects, "I don't do spaniels."

The all-volunteer revue has moved this year from the Trinity Theatre to the newly renovated theater at the Duke Ellington School of the Arts, 35th and R streets NW, where the show runs through March 29. The 1986 beneficiary is the Hospital for Sick Children, a pediatric specialty hospital in Northeast Washington. Last year the show netted more than $130,000 for the Columbia Lighthouse for the Blind.

Even the dead are not beyond the skewer in this roast. In "Mr. Halley," 20 eye-high-kicking, neglected celestial bodies cry, "We're working our tails off just to be stars" and stick it to the astronomer and his seldom seen apparition: "I am gonna vomit/ If I hear about that comet/ One more time."

But it's the living who really get burned. Geraldine Ferraro and David Stockman look-alikes extol the virtues of life after politics with a soft-shoe of "I Want to Be Rich." Princess Di remembers her visit to Washington: "When I had to go to J.C. Penney/ The only thing I wanted all day/ Was to wear my Sony Walkman/ And go far, far away." The ensemble sings U.S.A. for Africa's all-star anthem for famine relief, but this time Michael and Diana and the Boss are shouting out for the legal field: "We are the world/ We are the shysters . . . "

At each performance, a guest broadcaster reads the "Hexagon Update," a newscast in the mold of Saturday Night Live's "Weekend Update."

"This just in," WRC-TV's Steve Doocy announced earlier this week. "In a surprising upset, Ferdinand Marcos has been elected governor of Hawaii."

Broadcasters expected to deliver the "news" in future "Hexagon Updates" include WMAL's Harden and Weaver, WJLA-TV's Renee Poussaint and WRC-TV's Arch Campbell.

Others tentatively scheduled to make cameo appearances are former senator Eugene McCarthy, Lady Marjory Wright, UPI White House reporter Helen Thomas and Redskin Ken Jenkins.