Record of six minutes underwater-Riddle

Riddle

Magician Gogo holds the record of six minutes underwater. One day, Kushal challenged him, claiming that he could stay underwater for 10 minutes, without using any equipment or air pockets. Hearing this, Gogo offers him RS.10, 000 if he could do that. Kushal won the money, how?

    Kushal filled a glass with water and held the glass over his head for 10 minutes.