When Sam Witwicky accidentally activated the All Spark during his flight from the Decepticons in Mission City, the artifact's radiation animated a Mountain Dew soda machine into a robot, named Dispensor.
At an undetermined point in time, a mischievous Toaster took a poor man's last Mountain Dew bottle.
Capture the Cube
Transform Your Summer
The Earth was transformed into Dew City, where a green city covered the landscape, and all water was transformed into Mountain Dew. The cause is unknown, but may be connected to a near-collision of the All Spark and a Mountain Dew bottle in space.