The Blizzard is probably Dairy Queen's (DQ) bestselling ice cream treat. It is basically a blendered combination of ice cream with bits of sweets, like candy or chocolate -- over the years, many Blizzard flavors have been introduced. According to the Dairy Queen Oakville Website, "[t]he most popular Blizzard flavors include Oreo Cookies, chocolate chip cookie dough, M&M's, Reese's Peanut Butter Cup, and Butterfinger."

The Blizzard has consistently been on the Dairy Queen menu since 1985. It was said to be "modeled after the concrete treats of the Midwest from frozen custard shops like Ted Drewes in St. Louis, Missouri, and include the Ted Drewes' tradition of holding the cup upside down to demonstrate the thickness." So it is traditionally served upside-down as proof of its creaminess, and the unusual packaging and way of serving it is probably what customers loved best about it!

• The Blizzard has a nonfat cousin, called the Breeze, which is made of yogurt. DQ introduced this in 1990.
• Most DQ stores offer a Blizzard of the Month specialty. (The weirdest one I came across in is the Pumpkin Blizzard Treat.)
• The comic strip character Dennis the Menace was used as the DQ "mascot" from 1972-2002, but was removed when the marketing department felt that "children can no longer related to the character."
• There is an official Blizzard Fan Club. Mind you, this site is an unofficial fanlisting.

References: Dairy Queen Oakville Website, The New Dairy Queen of Barrie and Dairy Queen History by Katie Rykkeli.