Splat! Before the unassuming office worker knows what hit him, a smeared, cheese-filled burrito drips off of his computer screen. He retaliates, sending a bowl of chili flying at his co-worker. Fortunately for bystanders, the fight is restricted to cyberspace.

Lake Forest, Calif.-based Del Taco’s new viral marketing campaign, www.foodfightfiesta.com, encourages viewers to fling food at their friends via an e-mail with the subject line “Let’s do lunch.” Those who send an e-mail receive a buy-one-get-one-free coupon good for Del Taco’s Classic Taco.

While Del Taco’s is a particularly creative application, it represents part of a larger trend—that of discount couponing. According to one source, the use of coupons for quick-service meals has increased 198% since 2007.

The Del Taco campaign is a clear success. During the first week, the site averaged 2000 clicks a day. “We know it resonates with the younger [age] groups,” says Sharon Fogg, senior vice president of marketing for Del Taco. “I’m convinced that to be competitive in the QSR category, we have to have some version of viral marketing. Our target audience is online.”