TWO spotty, ugly youths, in scruffy (and presumably malodorous) AC/DC and Metallica T-shirts, are playing couch potatoes, watching pop videos on TV. Their conversation goes something like this: ''Hey, this video sucks. Huh-huh. It's full of men dressed like wusses.'' ''Yeh, I hate things that suck. They make me puke. Heh-heh. Switch it over.'' (They channel surf and land on a thrash heavy metal video depicting very loud guitars and blonde models with very little on.) ''Huh-huh. This is cool. Huh. Those dudes are cool.'' ''Yeh. Heh-heh. And check out that chick. She wants me. Come to me, babe.'' (Cut to the two teens headbanging while humming the riff to Whole Lotta Love, then proceeding to discuss what effect the babes are having on their lower anatomy.) This is the world of Beavis and Butthead, a year ago unknown apart from one appearance in an alternative animation short, now a nightly fixture on MTV and the biggest thing in youth culture since Wayne and Garth went ''schwiinnngg!'' or Bart Simpson told Homer to ''eat my shorts''.
Beavis and Butthead are crudely animated, crudely scripted characters who do nothing but be crude and perfectly obnoxious for half an hour, laugh inanely at every breath and turn scatology into an art form. The two supposedly south-western middle classyobs are nothing if not cleverly-observed representations of the Average American Teenager. Teenage viewers are seeing themselves in Beavis and Butthead - though they would probably not admit it - and making them the cult heroes of 1993. The B and B T-shirts, mugs and stickers are already on the production line and there is talk of a movie.