Is there such a thing as polka folk? Well there is now, sorta, among other things. Playing Gregor Mendel with their genres, I.E. is mostly folkie la Greg Brown but with added trombone, banjo, mandolin, guitar, electric bass, drums and various noisemakers that give the band the strange sounds of a group bent on being bent. Former Independent staffer Malcolm Lucard's lyrics are often of the cheeky, ironic and the-world's-so-wacky-and-messed-up-and-so-am-I variety with lines like "When I was young I wanted to walk on the moon/ Just like Neil Armstrong bounced around like a balloon./ He took a giant step for golf/ a giant leap for baboons." Don't let acid rain bog you down, and go have a knee-slappin' good time with Irrational Exuberance. The show's free. Call 328-1412 for more.