Our friends got home from church last Sunday night and immediately noticed that the porch light, which they had left on, was off, and the inside lights, which they had left off, were on.
When they went in the house, the wife noticed that her dishwasher was running. As they checked around, they looked into the den and saw the gray head of an older lady who was sitting on their couch, watching TV. The husband approached her and she said "You must be Marshall. The key you sent me didn't work, so I walked around to the back and let myself in through the back door." (The husband's name is not Marshall. Their son had forgotten to lock the back door before they left for church.)
Turns out she was there to celebrate Thanksgiving--with their neighbors. The husband walked her next door, carrying her luggage, to make sure she got there OK.
She had gathered their dirty clothes and put them in the laundry room, and she had straightened up the house.
I am not making this up.