Awww, they did the optical mouse trick. I was going to suggest that one. (It really does work, and will lead to calls to the IT Helpdesk.)

Ketchup one is the best.

The worst: One summer, I worked with Gil de la Rosa (your parents know him, Carlos!). He hated oranges, so I peeled an orange and put it in his car. This was his retaliation… We drove up to his house and there was an ambulance outside. Being good Christian summer missionaries, we waited across the street and prayed. After a few minutes, an EMT came out and said we could come in. When we walked in, we walked past the dining room where someone was laying on the floor, covered with a sheet. In the living room, the rest of the group, except for one, were sitting with there heads buried in pillows, shaking. The EMTs were in the kitchen with Pastor Gil, who started explaining to them what had happened. He said, “Well, the doorbell rang and Matt [the one person missing from the living room] and I both got to the door at the same time. I opened the door, and it was a man with a knife. He lunged at me, but Matt blocked him…and saved me.” The EMT asked, “Do you have any idea why this happened?” Pastor Gil replied, “I…I don’t know…I just know that none of this would’ve happened if Michelle Palmer hadn’t put an orange in my car.”

Matt wasn’t dead, but I cried afterwards anyway.