This is why I should never have children and retreat into academia forever.

Little kid, maybe 6 years old: Hey, I can't find the sticker on this book.

Me (realizing he means the barcode): It's on the inside. See?

Little kid: Why is it on the inside of this book? It's on the outside of this other one.

Me: Well, the placement of barcodes is done pretty arbitrarily...

Little kid: ...huh?