By Ethan Wolff-Mann
March 14, 2016
One customer filled up a vase.
One customer filled up a vase.

This year 7-Eleven is celebrating the 50th anniversary of the Slurpee, if you can believe it.

During the stores’ famous business hours on March 18 and March 19, the public will be offered a bizarre deal—you can fill almost any container you want with Slurpee for just $1.50.

Before you get too excited, there are some rules to the Bring Your Own Cup Day.

Size-wise, the container must be able to fit through a 10-inch hole. Yes, this could be a cylindrical glass that’s 10-inches wide and six feet tall—24 gallons. So you will be unable to use Slurpee to fulfill your childhood fantasy of bathing in a substance other than water.

The container must also be food-safe. You may think it would be cool to fill up an old cowboy boot, but this is not permitted.

It also has to be watertight—no having a secret hose to your car to siphon off the entire supply.

And you can’t bring two cups. Only one vessel per person.