From 11 am to 7 pm local time on August 18 and 19, at participating 7-Eleven locations, bring your own qualifying cup and fill it with Slurpee for $1.50. It's the first time we've seen such container liberty from 7-Eleven since May. In order to qualify, containers must fit through a 10" hole, be food-safe, and watertight. (Beer kegs and 5-gallon buckets are among those "containers" that won't work.)