Boo Boo

So the other day I took Briar and Avery on a walk while we were waiting for Sean to come home from work. I strapped Avery to my chest in the Baby Bjorn and Briar walked beside me holding my hand. Avery was bobbing along, gumming my thumb and Briar was weaving between the sidewalk and grass excitedly pointing out bugs and sounds.

"Buuug. One. One. One. "
"Pwlane. Puh-lane. PLANE."

"Yeah, thank you Briar, that's right. Bugs, lots of bugs and a plane! Good job, thanks for telling mom."

Then Norman, the incredibly friendly cat of our block ambled over to say hello. I thought Norman was kind of cool at first (months and months ago) now he's like that guy who you bump into way more than seems possible and who doesn't take the hint to leave until...well, actually he never takes the hint.
Anyway, we're walking along with Norman leading the way.

"Kitty. Ki-tee. Kitty, yeah."

Briar was reaching for his tail, sort of grazing her hand over the tip.

"Uh-oh. Oh no. Boo boo," she exclaimed.

"What is it honey?" I asked.

"Boo boo, kitty, boo boo," she said pointing ahead as Norman held his tail up, exposing his backside with feline pride.

"No honey, that's not a boo boo. That's, um, that's not a boo boo. That's how, that's where kitty goes poop," I explained somewhat dubiously. Would she get it? Should I explain what is it? Do I say butt? Anus? Should I...

"Yeah, plane!" she said with glee as she blew past Norman.

Whew.