Sinologists will know this one, but it’s rather fine, and can come in handy every so often.
Zhang the Third is worried someone will steal his hard-earned 300 taels of silver, so he puts it in a box and buries it in the earth near his house. But he’s still worried someone might dig it up—so just to be sure, he writes a note on the nearby wall:
此地无银三百两 Cidi wuyin sanbailiang
Here there is no silver, 300 taels
His neighbour Wang the Second comes along and sees the note. As he digs up the silver and takes it off, worried that Zhang might suspect him, he too writes a note:
It wasn’t Wang the Second next door that nicked it
Time for a cute kids’ cartoon (cf. here):