7-Eleven marks 50 years of Slurpees with $1.50 bring-your-own cup celebration

The Slurpee is 50 years old and to celebrate, 7-Eleven executives came up with a nifty promotion for this weekend. 

Declaring Aug. 19 and 20 to be #BYOCupDay, the convenience store chain promises customers all the slushy goodness you can fit into the vessel of your choosing, for just a $1.50. There are, however, a few simple rules you have to follow, according to company-registered website, slurpee.com

First, the “cup must fit upright through a 10” hole.” The cup almost has to be both “food safe” and “watertight.” Sloshing around a sticky Slurpee-drenched floor is a bit of a buzz kill, after all.

And lastly, while most 7-Elevens are open around the clock, this promotion is good Friday and Saturday between the hours of 11 a.m. and 7 p.m. local time.

Folks have taken to posting photos of their makeshift mega-cups on Twitter and Instagram. “I brought a pretzel barrel for #BYOCupDay at 7/11,” one Pennsylvania man shared on Twitter. Drink pitchers and plastic food containers also seem to be popular options.

7-Eleven conducted a similar bring-your-own cup day back in March.