Let's say that I need to call for Ricky from another room for something I need...I'll yell "hey Ricky?"
Now here's James in the background..."Wiiiicky!!!" Then I'm silently (well, trying to be silent) in another room laughing my butt off.
I respond with "James, you call him Daddy. Mommy calls him Ricky". James just walks away giggling.
I don't know when he'll understand this...