Free Slider at White Castle on May 15
https://www.prnewswire.com/news-releases/white-castle-showcases-archival-posters-and-ads-to-kick-off-national-hamburger-month-302133728.html -” get a free Original Slider on May 15, National Slider Day. No purchase is necessary. (Redeemable using code SLIDERDAY on the app or a digital coupon available on White Castle’s social media channels.)
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