Because

Sippy Cup (concentrating as he plays LEGO Batman 2: DC Super Heroes): "Dad, I can't beat this guy!"

Me (reading a magazine while sitting on the couch): "You have to keep trying.  You'll only get better through practice."

Sippy Cup (pleading): "Come on!  Just help me!"

Me (without looking up): "Dude, I don't even know how to play this game."

Sippy Cup (holding the game controller in front of my face): "Come on.  You have to."

Me (still reading): "I have to?  And why is that?"

Sippy Cup: "Because you're my Daddy.  And you're supposed to help me."

5 seconds of silence

Me (putting the magazine down): "Give me the controller."