We're not sure how this would have gone down.

Prince Harry has always been known as a bit of a character so his William was probably expecting something out of him when he asked him to be best man at his wedding. William married Kate Middleton in 2011 with Harry by his side - and it looks like Harry took his duties very seriously. The prince gave a speech at the wedding reception but had his then-girlfriend Chelsy Davy look over it. She reportedly got him to edit out a joke he had been planning to make about his new sister-in-law. According to royal biographer Kate Nicholls, she "helped Harry edit the best man’s speech, sensitively advising him to take out a line about Kate’s 'killer legs' that might have embarrassed the bride." Probably a good shout. Harry and Chelsy dated on-and-off between 2004 and 2011 after they met during his gap year. She even attended Kate and William's wedding with Harry but it proved to be a turning point for the relationship. The big day is reportedly what made Chelsy realise that she wasn't up for life under the glare of the royal spotlight. "Although they had a lot in common, she saw clearly that because they came from such different worlds it could never have worked, especially as she valued her privacy and guarded it so carefully," writer Angela Levin wrote in her royal biography Harry: Conversations with the Prince.