Person on Roller Skates Does One-Handed Cartwheel While Holding Glass of Beer in Other Hand

This person's partner challenged them to do a one-handed cartwheel while they were out roller skating and drinking beer. However, there was a catch. They were required to complete the challenge while being on their skates and holding their beer glass in the other hand. But after years of mastering one-handed cartwheels, they instantaneously completed this challenge without spilling a single drop of their drink.