One of my friends received a puzzle in the mail. This might seem innocuous, but she's worked as a public defender in New York and worried for her safety once or twice. It arrived in an envelope with no return address, and I think someone drew a skull and crossbones on the outside. She took it to the police station and said she thought it was poison. So she opened it and asked if she could put it together on the precinct floor. They acquiesced, and she spent some time before figuring out that it was a puzzle of the sculpture David. Then she took it home and began the hunt. Random brother in law? Former client? All signs pointed to no. It turned out to be from a friend who'd sent it right before going abroad. Life lesson: If you want to creep someone out, send them a puzzle with no attached explanation.