The act of ordering twice at a McDonald's Drive Thru in quick succession. Performed when the client intends to order a meal and a dessert. The Double Drive Thru ensures that the client's dessert (e.g. McFlurry, Cone, etc.) does not melt upon his/her completion of the meal. However, some argue that the Double Drive Thru causes embarrassment among other parties in the vehicle as well as the customer service representative at the Drive Thru window.
Spacely: Jay, why the fuck didn't you order your Oreo McFlurry?
Jay: Cause man, let me eat my double cheeseburger and then I'll order my McFlurry so it doesn't melt!
Flash: Oh my god you just pulled a double drive thru...