NICK'S KNACK

Says Cronin, deadpan: ''We think we can market Nick at Nite the same way Batman and The Simpsons have been marketed.''

Perhaps the most telling sign of Nick's success has been the way competitors have copied its campy style. The three major networks have been experimenting lately with their own Nickish promotional spots, splashing more colorful graphics on screen and affecting a wackier sense of humor. ''The networks are definitely imitating Nick at Nite,'' says Noah Edleson, a former Nick promotions producer now working for CBS. ''They're always asking me to do Nick at Nite ads for them — that's why they hired me. They love Nick's style.''

George Schweitzer, senior vice president of communications for CBS, says, ''We like the fact that Nick's ads take an attitude. They have an edge to them. It's hard to say who influences who in this business, but Nick's campaigns have definitely impressed us.''

Last May's ''Donna-thon'' — a.k.a "Seven Days That Tidied the World" — was by far the biggest promotional campaign Nick has attempted. In addition to the parade in Chicago, the network orchestrated a series of nationwide publicity salvos, including a four-page Donna Reed Mother's Day advertising supplement in People magazine. The ballyhoo seemed to pay off: More than 40 newspapers, from the Los Angeles Times to the New York Post, carried stories on the week-long Donna Reed broadcasts, a P.R. coup worth millions.

''We're the TV-generation network,'' Cronin says. ''If we don't run 70 straight hours of Donna Reed, who will?''