FREE: White Castle Slider May 15th May 14, 2020 By: Tricie share Head over to White Castle on May 15th and snag a FREE Slider for National Slider Day! Just print the coupon and take in to your local White Castle to redeem.Click HERE for Coupon. Love Deals? Be sure to find me on Facebook then COMMENT, LIKE, & SHARE the Deals! Please be advised that this post may contain affiliate links. See my Disclosure Policy for details.