Just a little idea I had a bit ago
In a movie about two criminals, one criminal send the date of the next heist to the other using a money based code. They send a check with the date of their next heist in the check’s value (e.g. $6.23 – 6/23/__). At the end of the movie, after pulling off an elaborate heist, one criminal opens his vault to find a that everything is gone besides a check for $4.01. April Fools Day.