"Dragon Ball Super" episode 16 is entitled "Vegeta Becomes A Pupil?! Take Down Whis."
In "Resurrection of F," Goku and Vegeta were already training under Whis. This week's "Dragon Ball Super" episode explained how they became Whis' students.
Attack of the Fanboy reported that "Dragon Ball Super" episode 16 showed Bulma feeding Whis lots of yummy human food. Actually, she is bribing Whis for protection for her and Trunks in case someone else tries to destroy Earth.
Vegeta learned that Whis trained Beerus, the God of Destruction. He also tried to impress him with food so that Whis can train him as well.
This part of "Dragon Ball Super" episode 16 showed a funny scene explaining how inept Vegeta is in cooking. At first, he went to restaurants but this does not convince Whis. Next, he tried to cook but cannot even crack eggs properly.
However, he managed to impress Whis with instant ramen noodles. Apparently, Whis loved the idea that this can be cooked with boiling water only. Vegeta then started training with him.
These scenes were shown in "Dragon Ball Super" episode 16's second hour. The first part witnessed Goku punching Krillin in the face.
At the start of this week's installment in the "Dragon Ball Super" series, Goku was shown sleeping on his tractor. Krillin showed up and talked to the Super Saiyan about his power.
Krillin felt that Goku has become even more powerful than him. AOTFB commented that although Goku was always a bit stronger, their power levels didn't have such a big gap.
Afterwards, it seemed like Krillin wanted to test his powers against Goku or he just wanted to prove that he can still keep up with the Super Saiyan. Krillin actually dared Goku to punch him in the face.
Furthermore, Goku actually punched his friend in the face. Krillin's black eye is left to Android 18's care.