Definition
To depress the accelerator to the maximum extent.
To move (run, ride etc.) at full speed.
Also Said As
- put the pedal to the metal
- fang it
- redline
- step on it
How People Actually Use It
To hit the acceleration pedal (or, in the US, gas pedal) to such extremities that it is parallel to the floor of a car. i.e. Hit maximum speed as quickly as physically possible.
"That fucker's getting away, FLOOR IT!"
Source: Urban Dictionary