THEY'VE dropped out of a time capsule. The Flying Karamazov Brothers are four jugglers who aren't related and haven't had their hair cut since JFK was elected. And their gloriously goofy stage act has its roots in an even earlier era: vaudeville.When the Flying Bros. K. mug for the audience, make bad puns, and bump into doorways a la the Three Stooges, you feel no compunction to look for deep, relevant meaning. You laugh your head off. You groan at the mention of quasi-pop '60s guru Donovan (if you are old enough to know who he was). And you realize that no matter how old you get, the sight of sharp objects being juggled always holds a thrill. Audiences have loved the Flying Karamazovs for nearly 20 years. The performers have kept some basic material, updating their between-juggling patter with Dan Quayle jokes and the usual political targets (Ted Kennedy went over big with the Harvard crowd). They've added some MTV twists: With drum-machine pads and other instrumental sensors strapped to their bodies and hooked up to a synthesizer, the brothers are able to strike the sensors with their juggling implements (in rhythm) to create full-blown rock music. Foot-stomping, bass-thudding rock music. High points of the show include juggling while tap dancing (or tap dancing while juggling); a free-form juggling jam session where the brothers have to sense the patterns in mid-throw; and "the Gamble," where the items to be juggled are provided by the audience. (The offerings one night included a bottle of Tide detergent, a car headlight, a plastic Slinky, and an umbrella. The Tide bottle was disqualified as too heavy.) Modifications are permitted, so the Slinky was rendered inoperable, but it and the o ther two items still proved impossible to juggle successfully. It's comforting, in this age of big-buck entertainment, that a stage-full of jugglers can reduce an audience to a bunch of giggling kids.
* The Flying Karamazov Brothers appear at the Hasty Pudding Theater, 12 Holyoke St., in Cambridge, until Dec. 31. The performances are presented by the Poets' Theatre.