A selection of words my 9-year-old finds inappropriate and/or hilarious

Ball
Sack
Bag
Thing
Dinghy
Stick  
Weiner (obvious)
Wean
Peony
Ball-peen hammer
Peeve
Pretty much any word that contains the sound "pee"
Crack
Hole
Naked
Nude
Hot
Bang
Boob (I meant it like "fool"! LIKE FOOL!)
Bra
Breast (preceding it with "chicken" only makes it funnier)  
Make out (like, "How'd you make out with that assignment?")
But
Butt
Butte
Panty
Girlfriend

(Why yes, I am living in a Matt Groening cartoon.)