On the way to Atlanta tonight, from the 4 year old:

Alex: Mom, squirrels climb trees.
Alex: Do squirrels pee?
Me: Yes, all animals pee.
Alex: Do dogs pee?
Me: Yes, ALL animals pee!
Alex: Do bears pee?
Me: Yes, ALL animals pee!
Monkey Boy: Do bears pooh?
Me: Yes, ALL animals pee and poop!
The conversation continued on and on! It started off really funny, but it got old after awhile.