It’s 7/11, known as Slurpee day by 7-Eleven. Today you can visit the local convenience store and get yourself a free 7.11 oz Slurpee. Anything free is good. And to celebrate here’s a free history of the slushee drink.

All great things like penicillin were invented by accident, so of course so were Slurpees. In the late 1950’s Omar Knedik’s soda fountain broke down so he put the soda in the freezer. He wound up with a slushee like drink that his customers loved. He then proceeded to capitalize on the idea by creating a machine to make the drinks all the time. He called his invention “ICEEs”.

In 1965 7-Eleven entered a deal with ICEE to sell the drinks at their stores. As part of the deal, 7-Eleven would not be allowed to call them ICEEs. In 1967 7-Eleven began selling “Slurpees”, named after the sound you make when drinking them.

The story I most associate with Slurpees is the one my Dad used to always tell me. He owned a 7-Eleven in 1969. When the Met’s won the World Series that year he gave free Slurpees out to anyone who entered his store with a Mets shirt on.

in 1970 7-Eleven gave out free records with Slurpee purchases with a song called “Do The Slurp”. The record is now considered to be highly collectable. If you really must hear the song, here you go:

If people actually listened to the song, it’d probably make the record much less valuable.

In July 2011 7-Eleven reached a deal with Cinemark theatres to sell Slurpees at their concession stand. It was the first time Slurpees had ever been sold outside a 7-Eleven. One year later a similar deal was reached to sell the drink at Six Flags.

After today you’ll have to pay if you want a Slurpee. So how about making your own instead? It’s easy! Just take any room temperature bottle of soda and shake it up. Freeze it for a couple of hours and then pop the top. It’ll freeze into a slushee in front of your eyes. Here’s a video with more detail: