When you pee in someones hair. The yellow in their hair will resemble a Super Sayian.

the thing that you don’t have when you’re phones percentage is over 20

A transformation used to receive a 50x multipler of your base form. Goku was the first person in the anime to achieve this form. It is abberviated to SSJ. There are other forms of SSJ such as Ascended SSJ, Ultra SSJ, Controlled Super Sayian, SSJ2, SSJ3, Super Sayian God and Super Sayian Blue. The only Sayians to ever achieve this form in the main series are Bardock, Goku, Vegeta, Trunks, Goten, and Gohan.