Storytime Gone Wrong

Its after 8pm. Kids have wiggled into pajamas, Vasco has emotionally recovered from his acrobatic and dramatic yet non-damaging slip and fall in the bathtub (which occurred 1.4 seconds after I said that jumping in the tub was perhaps not a good idea), and we are snuggled up on the couch, settling in for a few books before bedtime. Mostly what we do every night. Minus the tub acrobatics. So, I start reading an old favorite, "Goodnight, Moon" in my super special sleep-enticing story reading voice.
Me: "Goodnight moon, Goodnight cow jumping over the moon, goodnight light and the red balloon, goodnight bears, goodnight chairs..."
V: "mommy, chairs don't sleep...balloons don't sleep!!"
Me, continuing courageously, being caught completely unprepared to discuss this new development: "..Goodnight kittens, and goodnight mittens"..
V: "MITTENS don't sleep!!!"

I guess we may have outgrown that book..

On to the next old favorite: " Click Clack Moo".
8 pages of cow pictures later, Justine smacks her cute little finger straight down on the cow's udder and asks: "What's that?"
Me, smugly, because I know the answer to that one: "An udder. That's where the milk comes from."
J, looking up with great interest: "Where's the pee-pee?"
At that point, I did what I think is in technical appendix 9 of Chapter XII of any parenting book. I laughed until I almost (I said ALMOST!) peed myself.

And that concluded tonight's story time. I'll be preselecting my books much more carefully tomorrow. Any suggestions?