Here’s something I did a few weeks ago.
I had a pretty sturdy little box left over from buying a tie-clip. On the outside I painted a clue about what you would find if you opened the box:
On the inside some lights and a battery and a switch that turned off the lights when the box was closed and some wires and, you guessed it, A PIG!!!
A plastic pig. On a thumb-tack pedestal.
I made it and then I lost it, perhaps at North Bar. Wherever it wound up, hopefully someone found it and opened it in semi-darkness and got weirded out. It looked best opened in semi darkness, with the light coming out through the cracks kind of like that breifcase from pulp fiction (except the breifcase wasn’t labeled.)