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.
Synonyms for floor it
On this page, you will find 30 slang terms related to FLOOR IT. Some of the top words include: Hoon it, hauling ass, gussin, Explode, KriZ, and 25 more.