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If there’s anything that screams “SUMMER IS COMING” as much as a colorful frozen Slurpee, well, we haven’t found it yet. The sweet treat has been putting smiles on people’s faces (and giving us all massive brain freezes) ever since it first appeared at 7-Eleven back in 1965. Now, there’s a Trolli Pineapple Lime flavor inspired by gummy bears. There’s Cranberry Ginger Ale. There’s Piña Colada and Dr. Pepper and even a Sour Patch Kids flavor.

It makes sense, then, that to herald the return of sunnier days, 7-Eleven often gives the drink away for free. In fact, the brand has become known for its countless Slurpee promotions.

But this particular promotion—coming right when we’re starting to experience those first true signs of springtime—just might be its best, slushiest, most gratifying one yet. To celebrate National Sibling Day, which took place yesterday, Monday, April 10 (it’s not too late to give your sibs a call!), 7-Eleven is offering a buy-one-get-one Slurpee deal all the way through April 16…just as long as you come in with your brother or sister. From the sounds of it, a best friend or practically-a-sibling will work just as well, but personally, we’re not taking any chances. Besides, we’re 7-Eleven traditionalists. Real sibs or bust.

If you’re not getting out your calendar and making a game plan of which sibling you’ll be bringing each day of the week, along with their Slurpee flavor preferences, you’re not doing it right.

As for all the only children out there, never fear: It’ll only be a matter of time before the brand rolls out another icy-cold, delicious giveaway you can cash in on all by yourself.

This article originally appeared on Food & Wine by Rebekah Lowin.