The older kids have been playing with the concept of contracts, which has often involved attempts to trick the other into signing something. Like the time when Anna (6y) couldn't read yet and Lily (8y) prepared an unfavorable contract and "read" it to her by making up something with much more acceptable terms. We talked about how a contract requires both people to understand the agreement but it seems not to have stuck.
Yesterday the kids started exploring various forms of contract fraud. Anna wrote a very one-sided attempt at a contract, and didn't consider Lily's unwillingness to sign it to be an issue:
That's Anna forging Lily's signature. I explained that if you write someone else's signature it doesn't count, but it turns out this wasn't the right level of explanation. Lily got Anna to sign a blank piece of paper (an "I want your autograph" should have been very suspicious given the earlier contract shenanigans) and then pasted it onto a contract:
We talked about how that's also fraud, but they weren't very interested in my explanation.
I also wanted to get into how in addition to lacking mutual assent these contracts lacked mutual compensation and were probably substantively unconscionable, but they went off to play something else so I explained it to Nora (1y).