This is technically two freebies. The first is a coupon good for a free 16 oz. shake with the purchase of a regular priced sandwich. If you're thinking of eating lunch or dinner there any time soon, then don't miss this free dessert!
If buying something in order to get a freebie isn't your idea of fun (and if it is, you need to spend a weekend with me), then swing by on Tax Day (Monday, April 15) and pick up some free curly fries or potato cakes! You'll need to print a coupon, but it's not released until next Tuesday when the shake offer expires. I'm mentioning this now in the hopes that some Hiffers will remind me in case I forget!
EDIT: Here's the Tax Day Arby's page with the coupon.