AMC Theaters Coupon: Free Popcorn 01/12/2014 By Charlene 3 Comments This post may contain affiliate links, please see my disclosure policy. AMC Theaters is offering a mobile coupon for a free popcorn. No purchase necessary! Text BEST to 242424. You will need to consent to text messages but you can cancel that at any time. The coupon expires 3/6 so plenty of time to use it.