Anyone who sits down to watch God of Carnage has to realize that what follows won't exactly be realistic, says Kim Tobin, actress and co-artistic director of Stark Naked Theatre. Playwright Yasmina Reza's tale of the two couples meeting to discuss their children's playground fighting starts off ordinarily enough, but soon leaves the planet at the four parents involved behave increasingly, incredibly badly. ''It should feel uncomfortable and fun,'' she promises as these actors say all the outrageous kinds of things people think about saying, but usually (thank God) don't. And, in the end, she says, ''It's cathartic.'' Because, she says, audiences can walk out afterwards knowing that saying all those mean nasty things a) really don't get you anywhere and b) are going to make things a whole lot worse. Even if you've seen the movie and last year's production at the Alley Theatre (with visiting actors), Tobin promises the intensity will be ratcheted up even more in the small space afforded by the stage at Spring Street Studios. So be ready to duck as tulips and tempers fly and words and vomit spew forth. Local actors Tobin, Drake Simpson, Kay Allmand and John Gremillion star in the play directed by Justin Doran.