You were one of the strongest Saiyans in Planet Vegeta, hence it made sense for King Vegeta (who was also a good friend of yours),to make you a teacher to his 6 year old son Prince Vegeta but the young prince was against it,saying he dint need someone to teach him how to fight and how he already believed he was way stronger than you, of course in a sparring match you proved him wrong and he angrily got up looking at you "Ugh! No fair you cheated!" He says with a scoff about to..cry?