Dragon Ball Z - episode 53 - 26 Jun, 1990

Realizing he is no match for Vegeta's increased power, Zarbon has no choice but to reveal his true power, transforming into a hideous reptilian beast. In this form, he is far more powerful, and begins to pound Vegeta. With a mighty stroke, he blasts Vegeta to the bottom of a lake, and he is presumed dead. (Source: Wikipedia)