PHILADELPHIA (CBS) — Slurpee-enthusiasts, March 18 and 19th are for you.

“Bring Your Own Cup Day” takes place this Friday and Saturday from 11 a.m. to 7 p.m. at all U.S. 7-Eleven stores.

Customers can bring their own cup and fill it up with their favorite Slurpee flavor.

There are some rules: the cup must be able to fit upright through a 10-inch diameter hole, the cup must be food safe, it must be waterproof and you can only have one cup per person.

It will cost you $1.50.

For more information, click here.