It's a simple idea, really--making an avant-garde play about avant-garde plays--and so well executed here that it traces a new direction in the avant-garde. Clowns Plus Wrestlers incorporates many of the most current ideas in avant-garde theater: a fragmented plot made up of several miniplots that intentionally go nowhere, New Vaudevillian clowns, text appropriated from other sources, postmodern dance. The new element in this stew is its two wrestlers, small-town boys who speak leaden English and want to prove their manhood by violently overcoming other men. Their crudeness makes the rarefied theories of the avant-garde seem silly, but the clowns put up a spirited defense with a series of clownish debates on nonsensical topics. The battle lines are clearly drawn: the wrestlers are like those fierce deconstructionist critics who want to wrestle all the meaning out of a text, and clowning is the only possible defense against such serious men. But they can't wrestle the meaning out of laughter, and in the end the clowns hold the upper ground--just as in the end this short play's giddy nonsense is more memorable than its bone-crunching wrestling. Cook County Theatre Department, 2255 S. Michigan (enter on 23rd Street), 842-8234. Through April 30: Fridays-Saturdays, 8 PM. $6.