Everyone knows about Super Saiyan. But super saiyan master is that formed even grater than of Super saiyan 3. After vegeta and other z fighters were defeated against the fight with Great grand kid of Evil Buu. Goku was so angry and upset about his friend that he charged up and trusted heavly towards the Evil Buu Jr but Goku appeared to be no match for the feat Evill Kid Buu Jr. Goku was pissed up so badly that he went berserk and reached a stage called Mastered SSJ. With this form Goku easily defeated the Evil Kid Buu and Vegeta was lying on the ground and talking about Goku.
.After the battle was over Vegeta said to Goku; Goku my friend you are the best and you are far better than me in everything.