Writing in Vanity Fair, he said:" When I was a stand up comedian in the late 80s, I used to open for Jim Carrey on the road. I would do my lame act and then he would come on and do the most energetic, inventive, uproarious set I had ever witnessed. I retired from performing as a result. He was and is the funniest man on earth. This is something we can all agree on. We can debate number two forever but Jim will always be the king."
Jim, 50, recently splashed out $160,000 to hire a private boat for the cast and crew of his new film 'Kick Ass 2' and took them on his own guided tour of London's sights down the River Thames.
A source said: "He didn't get a single point of interest right, but his version of London's history was much more entertaining."
The funnyman played tour guide to the likes of Nicolas Cage, Chloe Grace Moretz and Aaron Johnson and kept his guests entertained by performing a rendition of The Proclaimers' 'I'm Gonna Be (500 Miles)' as they sailed down the river.
Jim was celebrating landing the role of Colonel Stars in the sequel to 2010's wacky superhero comedy after expressing his love of the original 'Kick-Ass' film by Matthew Vaughn.