(FORTUNE Magazine) – ONE OF THE HOTTEST STARS in the advertising firmament is Fallon McElligott Rice, a 3 1/2-year-old agency from, of all places, Minneapolis. In January it landed a $5-million account to drum up subscribers for the Wall Street Journal. In snagging the business, the Minneapolis upstart triumphed over a couple of New York heavyweights. It evicted BBDO, the Journal's agency for nearly 40 years, and beat out Lord Geller Federico Einstein, the J. Walter Thompson subsidiary that plugs the IBM Personal Computer. Says President Patrick Fallon, 39, ''We're selling imagination, and imagination can come from anywhere.'' The Minnesota brand of imagination combines wit, irreverence, and shock. To promote Minnesota's Gold'n Plump chickens over poultry from the South, the agency hatched a television spot featuring live helmeted chickens, some in parachutes, others in tanks, all combat-ready to guard the state's borders against fowl migrants. A campaign for Minneapolis-based ITT Life Insurance Corp. pushing term insurance over whole life policies featured newspaper ads , that proclaimed: ''Your whole life is a mistake.'' For the Episcopal Diocese of Minnesota, which wanted to remind people of the meaning of Christmas, creative director Thomas McElligott, 41, whose father and father-in-law are clergymen, depicted Santa Claus and Jesus on a poster that asked: ''Whose birthday is it anyway?'' Fallon McElligott Rice claims its attention-grabbing ads get results. ITT got 12,000 responses to its ad, more than three times its goal. The chicken troops helped pluck Gold'n Plump's market share from 35% to 45% in Minnesota. Fallon and McElligott first teamed up in 1974 in a part-time, freelance venture, Lunch Hour Limited. At the time, Fallon directed marketing at Martin Williams, a Minneapolis agency, while McElligott was creative director at rival Bozell & Jacobs. The partnership allowed them to write the kind of offbeat copy they say their own agencies rejected. In 1980 the two decided to go full time. They spent the next year readying their business plan and lining up recruits: Nancy Rice, 37, now art director; Fred Senn, 41, account executive; and Irving Fish, 42, chief financial officer. The five ponied up $200,000, opened shop over Peter's Grill downtown, and issued a full-page birth announcement in the Minneapolis Star and Tribune: ''A new advertising agency for companies that would rather outsmart the competition than outspend them.'' Within a month the newcomers had $4 million in billings. To promote itself beyond Minneapolis, the agency spent $45,000 to enter scores of advertising competitions. It won enough of them to get the attention of the Wall Street Journal, which invited Fallon McElligott Rice to submit a campaign for increasing its circulation--at 1.96 million, it has sagged 3% from 1983's level. The Journal says the winning campaign offered ''a new, creative, and exciting approach.'' But neither the newspaper nor the agency will say whether that approach will be the one that the Journal will introduce this spring. The Journal business brings Fallon McElligott Rice's annual billings to about $48 million. Says McElligott, ''Once you get over $50 million, growth becomes a source of anxiety.'' He says that the agency, which employs 65 people, has already gobbled up all the talent in the area and is still understaffed. To grow, Fallon McElligott Rice will have to persuade bright young copywriters, as well as national advertisers, to abandon Madison Avenue for Minneapolis's Fourth Avenue South.