Barbara Davilman and Nina Tassler have just the thing for hearts who—sadly or gladly—wind up lonely on Valentine's or any other day: get-lost cards. These are mischievous little missives for when you care enough to send the very nastiest. One number sweetly asks an ex-lover, "What two things come in summer and fade in the fall?" The answer inside: "You and my tan."

Davilman, 24, and Tassler, 25, who worked at the same Manhattan ad agency, launched their firm—Bittersweet Cards, Inc.—last year. The idea, recalls Barbara, "came out of a need. I was dumped by a guy I'd dated for three months. He stopped calling." She considered writing him a letter, then decided "all that needed to be said I could do in 15 words. So I scribbled, 'I didn't realize the last time we kissed I was being kissed off.' " After she showed her scribbling to Tassler, they stayed up into the wee hours composing more such billets dour. "When they were still funny the next day," says Nina, "I knew we had something."

Within a week they hired an illustrator, Debby Young. In August Nina made the first deliveries to New York stores, using a shopping cart. Three weeks later they had recouped their $10,000 investment. Now their 36-card line is distributed nationally. The cards (price: $1) variously express revenge, reconciliation, apathy and guilt—"all the emotions you go through in a relationship," says Davilman. What about love? "If you want bliss," she advises, "go to Hallmark."

As for her ex-beau, "I did call and ask him to dinner," she admits. "I told him I needed more inspiration for our cards." She then sent him some samples. Alas, they worked all too well: She's never heard from him since.