Check out this great sketch parodying how Floyd Mayweather taught Justin Bieber boxing from late night talk show, Conan. This comes from the story that Bieber came to the boxing champ wanting to learn a thing or two about boxing, and Mayweather duly obliged. There are some videos of the lessons circulating online but, in all honesty, Conan O'Brien's version is a lot better.
If you've ever wanted to see an elite boxer whale on the androgynous Canadian pop superstar, this is about as close as you're going to get. A lot of people would pay good money to see this happen in real life.