It does matter on May 19th and 20th!!
Valid on May 19th and 20th from 11AM to 7PM, head to 7-Eleven to take advantage of Bring Your Own Cup Day! You’ll be able to bring your own cup (think BIG) and fill it up for $1.50! They do have a few guidelines that you must follow:
Size matters: Your cup must fit through a 10″ hole.
Keep it clean: Your cup must be food safe.
Plus the leaks: Your cup must be watertight.
Slurpee for all: One cup per person.