Smarty Pants

Luke got a Madagascar toy in his happy meal yesterday and wanted to know the zebra's name. This conversation followed:
Me: His name is Marty.
Luke: Smarty?
M: No - it's Marty.
L: Smarty?
M: No, there's no S. It's not Ssssmarty, It's Mmmmarty.
L: OK.
Mind you, this actually went on in the same way for quite some time!
After 10 minutes or so of silence in the back of the van as they watched their movie, Luke all of the sudden yelled out, "Smarty is funny!!"