Roses Are Red, Blue Jeans Are...

Roll over, Robert Frost. Quit howling, Allen Ginsberg. Chill, Sylvia Plath. America has a new Most Favored Poet. If you've watched TV in the last month, you know him well: 43-year-old Max Blagg, the very dapper, very downtown poet whose ''What Fits?'' is the soundtrack to a commercial for Gap jeans.

You know the poem: ''Sky fits heaven so ride it/child fits mother so hold your baby tight/lips fit mouth so kiss them...'' and so on, read by Blagg while actress Mädchen Amick (Twin Peaks) models jeans that fit ''like a glove/like an old lover coming back for more.'' Gap's in-house ad agency commissioned the poem from Blagg, who was tending bar in New York City, and hired photographer Matthew Rolston to direct the commercial.

Since then, the ad and its viewers have developed a strange love-hate relationship. ''What Fits?'' has been scorned by some, lovingly adopted by others, recited in high schools, and deftly parodied in a series of NBC program promotions that used '60s pop poet Rod McKuen to spoof the ad's smoke- coffee-and-bongo-drums Beat mystique. ''Our spots were meant as flattery,'' says NBC vice president Vince Manze. ''If some people thought the Gap ads were pretentious, so what? They had everybody talking. In advertising, that's what's important.''