From Dragon Ball Encyclopedia, the ''Dragon Ball'' wiki
Goku shouts, "Ka... me... ha... me..." and backflips multiple times before facing his opponent. He then shouts, "...ha!" and fires a Kamehameha from his feet, launching himself at his opponent and leaving him free to attack with his hands, thus serving as a great advantage.
Goku used this attack in his match against Piccolo at the 23rd Tenkaichi Tournament. After exchanging blows with Piccolo up in the air, Goku got hit and started falling down to the ground head first. Just before he hit the ground, however, Goku fired the Feet Kamehameha at the ground, launching him back up into the air and double-punching Piccolo in the face.