DB Episode 120
From Dragon Ball Encyclopedia, the ''Dragon Ball'' wiki
Goku starts his fight off throwing King Piccolo through Chow Castle. King Furry watches the fight in amazement. King Piccolo first attacks fail to harm Goku. All this time Tien is stunned by Goku's new power. Piccolo gets many blows from Goku, so he harnesses his full power, killing Piano in the process. Goku takes a powerful hit and Piccolo rounds on Tien. Goku suddenly leaps about to launch a Kamehameha wave.