CHICAGO — You'll be able to grab a free, mustard-covered hot dogs for the Crosstown Classic this week.

You can thank Heinz ketchup: The condiment powerhouse tricked Chicagoans into eating ketchup-topped hot dogs for National Hot Dog Day, and mustard-maker Gulden's was so outraged it decided to fight back. (Although it turns out quite a few people here secretly like ketchup.)

On Monday, Gulden's will hand out free hot dogs topped with its signature mustard at the Wiener Circle, 2622 N. Clark St. After all, the Wiener Circle is "the most vocal hot dog place in Chicago," according to Gulden's, and they're no fans of ketchup.

"No Chicagoan would ever put ketchup on a d--- hot dog," a worker at the Lincoln Park stand said in a video Gulden's created to expose Heinz's stunt. "Mustard, relish, onion, pickle, tomato, celery salt. F--- the ketchup."

Here's where you can get free hot dogs from Gulden's:

• 11 a.m.-2 p.m. Monday at the Wiener Circle, 2622 N. Clark St.

• 11 a.m.-2 p.m. Tuesday at Chicago's Dog House, 816 W. Fullerton Ave.

• 4-7 p.m. Wednesday at America's Dog, 700 E. Grand Ave.

• 4-7 p.m. Thursday at Chubby Wieners, 4652 N. Wester Ave.

Watch Gulden's video: