It would be hard to come up with a cheaper ad campaign: Mars' new fruit-candy promotion consists of redirecting its homepage to a Twitter search for "Skittles." Successful? Wildly.

A Skittles logo floats on top of the Twitter page, and sometimes Mars redirects to YouTube or Facebook instead of Twitter. The campaign is about as bargain-basement as you can get: Mars doesn't need a TV buy, ad agency or even much Web design work.

And Twitter users are, as planned, including the word "Skittles" in their posts in order to have the honor of appearing on the home page.

Many of the things people type about Skittles are inappropriate and insulting, obviously, which doesn't sit well with some uptight marketing wizards. "Everyone is having a field day and writing 'Skittles' on Twitter just to get attention," an executive at Microsoft's digital-marketing firm sniffs to the Wall Street Journal.

Right, but Mars doesn't care what people say about its product, specifically. Everyone knows what Skittles taste like, and every bag is exactly the same. The company just wants people hearing "Skittles this" and "Skittles that" over and over again until they haul their butts down to the corner store or office vending machine.

In other words, Mars has reduced its advertising nearly, but not quite all the way, to mindless repetition of a single word. Sort of like how it reduced candy nearly, but not quite all the way, to pure colored sugar. With Skittles.