v. phr. 1. To push down on the gas pedal to make a car go faster. Be very careful when you step on the gas. Don't go too fast.
Compare: GIVE IT THE GUN. 2. informal To go faster; hurry. Step on it, or we'll be late for school. John is a slow starter, but he can step on the gas when it looks as if he might lose the race. Lee was wasting time at breakfast and his father told him to step on it or they would miss the bus.