He doesn't think he's funny, but he is incorrect. Check out the story he told on David Letterman about defacing a 21 Jump Street billboard of himself with paint, on roller skates, at 2:00 in the morning.
During press for Rango, he was asked if he was a Belieber. As his young daughter Lily-Rose is a big fan, he said yes, and young Master Bieber entered the room very shortly thereafter, causing Johnny to wonder if he'd "conjured him up" in some way.