Still wondering why he finds this pun so hilarious?
Maybe if I spell it out for you a different way:
Or if I show you a graffiti image I found, after a member of our church pointed it out, outside our front door yesterday: (feel free to click and enlarge for full effect)
Now dear reader, your mind may wander to that 'potty place' and you will understand this type of humor.
I would like to put out a special thanks to Dav Pilkey author of Captain Underpants for planting those seeds of pre-pubescent boyhood dirty-mindedness. You really got a good thing going there. You started him into a love of reading that's for sure. Now can you make him stop with the poop head drawings? Got a book for that Mr Pilkey?
(actually I laughed just as hard at the violin tooter comment- I'm no prude, I just like keeping that sort of thing away from the churchy people who come to my door)