White Castle celebrates National Slider Day on May 15th by offering customers a free cheese slider. You can claim this freebie by presenting a digital coupon at any participating White Castle location. No purchase is necessary to enjoy this offer. 

A slider at White Castle is a small, square hamburger that's known for its unique preparation and distinctive taste. White Castle pioneered the slider concept, and their burgers are typically steam-grilled on a bed of onions, which infuses them with flavor. The original slider includes a small beef patty, onions, and a pickle slice between two small buns. Over time, they've expanded their slider menu to include chicken, fish, veggie, and breakfast sliders, offering a variety of choices to suit different tastes.