From Dragon Ball Encyclopedia, the ''Dragon Ball'' wiki
Planet Voon (惑星 ズン, Wakusei Zun) is a planet in the North Galaxy.
Dragon Ball Z
Planet Voon was homeworld of the Voonians. It had ten times the gravity of Planet Earth, however, the planet's appearance suggested that it was a somewhat harsh and desolate place. It was introduced during the Babidi Saga when Son Goku, Vegeta, and Son Gohan were in Babidi's Spaceship. When the three Z Warriors were on the first level of the spaceship, they used Rock-paper-scissors to decide who would go first. Vegeta was the victor, and got ready to fight against Puipui. Soon afterwards, Babidi transported Puipui to his homeworld so that he would have an advantage while fighting against Vegeta, however, Vegeta effortlessly slaughtered Puipui within minutes without even going Super Saiyan or Super Saiyan 2. The planet was never mentioned again.
It is named Planet Zoon in Dragon Ball Z: Buu's Fury.