When I was about 9 or 10, my parents renovated the kitchen in our house. This led to us spending some time with a kitchen that led my cousin Matt, then 3 years old, to walk into the room at a party and announce, "Hey Aunt Laurie! You got no walls!"
I'm not sure exactly what my inspiration was, but at some point I decided that it would be funny to take advantage of this situation to play a trick on the contractor who was doing the work on our kitchen. I wrote a note, crumpled it up, and spent a few days soaking it in tea or coffee and aging it in the sun. Then I folded it up and hid it in the wall before the contractor was going to close the walls. The note was dated to 1931, the year the house was built, and, using my best formal and old-fashioned 9-year-old vocabulary, said something along the lines of
To whom it may concern:
Be it known that this is an important and historic house and should always be preserved undisturbed. Ensure that no one damages or changes this important building. By the time you have reached this note, you have already done irreparable damage to this valuable building.
[Man who built the house]*
(Note to 9-year-old me: buildings are not generally referred to as "historic" the same year they're built.)
I sat back and waited for the contractor to find the note and be horrified that we had made changes to this important historic building! It never happened. I'm sure they just put up the sheet rock without digging around too much behind the studs. (This is about what you'd expect, given my track record of successful pranks as a kid (or an adult, for that matter.)) My note is still behind the wall, if it hasn't disintegrated already, probably attracting bugs with its remnants of coffee and tea. Should some other homeowner ever try to renovate the kitchen in that house, I am confident that they will not fall for my little joke . . . but I'm not exactly sure what they'll make of it, either!
*I can't think of his name at the moment, but I knew it at the time and may be able to look it up next time I'm home.