It may be "that awful dentist's-office music," as one student called it, but at the University of Virginia, where the only thing worse than being expelled is being tacky, they're planning to install a new telephone system with--gasp--Muzak.

"Who wants to hear the mariachi arrangement of 'Boogie Woogie Bugle Boy' when they call a selective university?" said Laura Bligh, a 22-year-old English major who has spearheaded a petition drive on the Charlottesville campus against the "mindless imposition of Muzak for the masses."

"We are rather into dignity simply because of Mr. Jefferson," said Bligh. Mr. Jefferson is, of course, Thomas Jefferson, who founded the university 163 years ago and is revered there as a cult figure. "Mediocrity is what we should avoid at all costs."

Robert Kellogg, dean of the School of Arts and Sciences, and one of 500 people who signed the petition, agrees. "I must confess that I'm a little concerned about our image, particularly when people from other universities call. After all, they might be used to this when they call Trailways or Greyound, but not when they call the University of Virginia. It's really amazing: Who wants to be forced to listen to xylophones and things?"

University officials say suggested alternatives to reassure callers they have not been disconnected--among them music by Vivaldi and Bach, the sound of waves crashing against a beach or "white noise" such as the hum of an air conditioner--simply will not do. Consultants have recommended Muzak as the least expensive component of a sophisticated computerized phone system for which the university paid $7.5 million.

"Besides Mr. Jefferson loved music and he loved gadgetry," said an amused William Fishback, associate vice president for university relations. "I don't know whether he'd care for music on his phone.

"I would hope it would be on the classical side," said Fishback. "Of course, other people might prefer Hank Williams or Bing Crosby singing 'White Christmas.' "

Despite statements by university officials that the new system, Muzak and all, will be fully installed by mid-August, Bligh says she plans to continue circulating petitions opposing it.

"I honestly don't think it will do any good," she sighed. "When I sat on the lawn and collected signatures, people asked me why I wasn't campaigning against poverty or hunger or wars abroad. Well, a lot of people are working against those things, but nobody is campaigning against Muzak . . . . One has to make a gesture about the little things in life."