A Hippo Named Boo Boo. Period. End of story.

We recently had a sitter come over to the house and while she was there she read the book, "The Book with No Pictures", to the boys.  We run a pretty tight ship around here regarding potty-talk and naughty language.  There are some words that we just don't use.  Such as "Shut-Up", "Pee", "Butt", "Bucket Head" and "Boop".  (The later two which will be stories of their own at some point.)  In my opinion, these words are gate-way cursing and I know that they will quickly get abused in this house of boys (which is exactly what happened to "Bucket Head" and "Boop").  Well... In this book it uses a potty word.  It's not a problem because I always just skip right over it.  However, on this day, the sitter didn't know better and it was read, aloud, to the younger 2.  (Well, C3 really didn't care, but C2 was on Cloud 9.)  You would have thought that he just discovered the 8th Wonder of the World.  I didn't realize this discovery until I sat down a couple of hours later to read to them before nap.  C2 got THE biggest grin on his face when he handed me his choice of books.  I did find it a little odd that his grin was so big, but I'm no dummy and started to put the pieces together rather quickly.  So... I started reading the book.  The suspense grew.  He was getting antsier and antsier for me to get to "the page".  I finally got there and read it as I always have, "My best friend in the whole wide world is a hippo named Boo Boo.".  He looked at me eagerly and said, "What else??" I couldn't help but chuckle.  I said, "Oh... do you think there is another word?"
C2 shouted excitedly, "Yes!!! A POTTY word." Giggling contagiously.
I quickly responded, "Well, we don't say potty words in this house, so I don't read that word."
Total disappointment fell across C2's face.
Later that day it was time for books before bed.  This time I had all 3 boys in the room with me.  The suspense was building for C2 again.  His grin was soooo wide!  C2 could not wait to show his older brother his discovery from earlier in the day.  I overheard them whispering and flipping through the pages.  C1 is not a huge book reader, especially when he is the one that has to do the reading.  That night he was so motivated to read through the entire book until he found the treasure.  The coveted potty word!!!