You’ve seen it around: a giant creature with menacing buckteeth, long claws, and red, beady eyes. It’s a regular at union protests and strikes, wherever there’s labor tension. If the Rat could speak, it would get right to the point: “So I moved your #@!% cheese. You wanna do something about it?”

It was another busy year for this indefatigable inflatable. It lurked at construction sites for a Wal-Mart in Watchung, New Jersey, and a CVS in Bradenton, Florida. It glared at a GE plant in Schenectady, New York, and a Starbucks in Chicago. Two of the rats even landed in police custody for a few hours after a protest in Troy, New York–“for questioning only,” a police spokesman said.

Twelve years ago, Mike O’Connor, owner of Big Sky Balloons & Searchlights in Plainfield, Illinois, created the first rat at the request of a union member in nearby Chicago. Said the union man of O’Connor’s first sketch: “It’s not mean enough.” O’Connor added bigger fangs and a pink belly with “festering nipples.” “I love it,” the man said. So did other unions. Today, Big Sky sells between 100 and 200 rats a year–even though it is a nonunion shop itself.

The Rat comes in several sizes, from the squat-looking 6-footer ($2,000) to the towering 30-footer ($7,700). Because many communities have ordinances limiting the height of inflatable displays, the most popular size is the 12-footer, small enough to stand upright in the bed of a pickup truck, yet big enough to attract attention.

Does the Rat work? “Usually, employers go bonkers when they see it across from their property,” says Randy Mayhew, organizing director of Laborers International Union of North America, which employs about 20 rats. “It’s an effective piece of street theater,” says Peter Jones, executive director of the Labor Heritage Foundation.