Sort of thing. It's not going to be fun when your child understands that there is no school on weekends, you'll lose a lot of trust overnight with this.
I think this is another case of a joke that people have taken seriously. There's no chance this would work in reality. It just makes for a funny hypothetical.
I guess for some people the dumber you are the more impressed you are with your own ability to fool a child. Probably because that's the last stage of their child's life where they can still pretend to be smarter....