Why is "Mikey" always the stupid one?

I named my boy Michael and he was born in 2006. We picked this name based on some relatives and the fact that is was a real guys name not some made up name like some of our friends were doing including mis-spelling normal names to make it unique. I never considered the name Mikey, Mike or Michael to be associated with an idiot. Mikey was the one that understood the cereal was good.