Tommy's joke

You know the banana knock-knock joke?  Tommy has his own version. 

Tommy:  Izzy! (or Grandpa, or Dad, or Ryan, etc) 
Izzy: What?
Tommy:  Izzy!
Izzy: What?
Tommy:  Izzy!
Izzy:  What Tommy?
Tommy: (pause)  um...Light!!!

Ok, so it's not really a knock-knock joke, more of just an irritating and common occurrence.  Except that I think it's funny and delightful, it's mostly just the kids who find it irritating.