To celebrate their birthday, 7-Eleven convenience stores are giving away free 7.11 ounce Slurpee drinks all day next Monday (from 12:00 am on July 11 until July 12 at 12:00 am). Check to find a 7-Eleven store near you.
There is actually a Wikipedia entry on Slurpees in case you want history, a flavor list, and trivia about the Slurpee drink. For instance, chilly Winnipeg Canada is the world leader in Slurpee sales, selling 188,833 Slurpee drinks each month. Also, in Australia the free Slurpee day is November 7 (7/11) instead of July 7 (7/11), since that country uses day/month instead of month/day like we do in the US.