Grab your dog’s huge water bowl or your favorite drinking boot: It’s time for Bring Your Own Cup day at 7-Eleven.

Today and tomorrow, anyone visiting a 7-Eleven between 11 a.m. and 7 p.m. can fill a vessel of their own choosing with Slurpee and pay just $1.50.

Same as last year, there are a few ground rules that keep you from filling an inflatable pool or a giant trash bag:

• All cups must be able to fit upright through a 10-inch hole (stores have a cutout to measure this).

• The vessel must be food-safe and water tight.

• Limit is one cup per person.

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