If you were given the clues ''British dramas, Barney, and prime-time game shows,'' would you answer, ''Things you see on PBS''? You should, now that the educational network has added Think Twice, a weekly Jeopardy!-style brain-strainer, in an effort to broaden the PBS audience. Well, if public television really intends to take off its bow tie, muss up its hair, and mingle with the masses, why stop with a game show? Here are other makeover tips PBS should consider.
*Give Firing Line's William F. Buckley Jr. a nanny sidekick with a grating Queens accent and great legs.
*Add sexy intrigue to Sesame Street and rename it Melrose Street. (Cut away when Bert and Ernie kiss.) Or reunite the kids from Zoom who are probably in college by now and create Boston, Mass., 02134.
*Merge The Frugal Gourmet and Yan Can Cook. Call the new show Love & Wok. Watch as cultures clash and wacky high jinks ensue.
*On Joy of Painting, make Bob Ross throw in a couple of nudes every so often.
*Have Diana Rigg explore cases involving UFOs, ghosts, Bigfoot. Call it Unsolved Mystery!
*Add naked butts to Prime Suspect.
*Give Charlie Rose a band and a sparkling city backdrop.
*Add aliens and a spaceship with a bald captain to Nova.
*Bring Steve Thomas' wife and son into This Old House and make fun of his dopey male posturing. Put Bill Moyers peeping over the backyard fence, offering mystical words of wisdom.
* Turn Evening at Pops into Evening at Pops Unplugged.
* Get Mr. Rogers out of cardigan sweaters and into Lycra. Give him some pizza- chompin' martial-arts-lovin' sonic mutant morphin ranger turtle neighbors.
*Combine Rough Guide with Where in the World Is Carmen Sandiego? Give the hosts guns.
*Get Jerry Lewis to host pledge drives.
*On occasion, let Barney eat a child.
* Run commercials.