Cat in the Hat ethics

I read the Cat in the Hat to my boys last night and as you are probably aware, at the end of the story after all the chaos of the day, the mother arrives at home and the last line is “now what would you do…” or something like that. In other words, tell her what happened–or not? My oldest said, “I’d just say I was sitting in the chair the whole time” with a smile on his face. I said, “That would be a lie right?”
He said, “yes, but I don’t want to get in big trouble.” Situational ethics from a seven year old.