IMAGINE A MAN watching television at home (not hard to imagine). On the TV screen, a huge amount of money and energy is being expended during almost every commercial break to get him to eat hamburgers from one or another fast-food restaurant, and to do so right now, this very Sunday afternoon. But he doesn't really need a hamburger, and neither, he reminds his children when they raise the topic, does anyone else in the house. Besides, he notes smugly, they're miles from a hamburger stand.

"Superb choreography, great songs and some wonderful plot lines," the man muses. "All to sell hamburgers. What'll they think of next?" Then he smells the fried onions.

"John," his wife calls to him. "There's a trailer parked outside and -- would you believe it? -- they're selling hamburgers from it."

"We want some!" the children shout. "We want French fries too!"

There was a report in this paper the other day that Burger King, the second-largest fast-food outfit in the country, is experimenting with mobile restaurants -- wagons capable of serving pretty nearly its whole line of food. It is dispatching them to campuses, parks and beaches in Florida, although probably not to your street yet. "We think it's going to become a major part of our restaurant system," said an official of the company. "There are so many places where there is heavy food traffic but people don't want to get in their cars and drive to find it."

Burger King isn't alone in this. Several other fast-food corporations are preparing to roll out their own fleets of wagons. "It's a logical evolution of the whole fast-food industry," said one executive.

He's probably right. And as the fast-food industry continues its logical evolution, somewhere a woman is calling, "John, where are you? Didn't you hear the kids say they want money for the hamburger wagon?" But her calls go unheard because her husband has fled to the attic and pulled the ladder up after him as he seeks a respite, however brief, from life in the fast lane with the heavy food traffic.