Vaseline under the door handles... a lot of it, enough to fill up the space.
Banana in the tail pipe.
Sardines on the exhaust manifold.
Pull the fuse for the heater/blower.
Pull the fuse for the radio.
Advance the plug wires one socket ahead of the proper sequence (easily replaced).
Use an eyedropper and put hot water inside the door locks. As cold as it is...
Remove the front seat(s).
Remove the steering wheel.
Put a rock or two in a couple of hubcaps (if the car has them).
Use masking tape (comes in different colors), "graffiti" the car up good.
Using a car marker (like used car lots use to write prices in the window), color in the windows and windshields. White or yellow works beautifully.
Straight wire the horn to a spark plug. The results are absolutely maaaahvelous.
Disengage the transmission linkage.
"Steal" the car's hood. Prop it up against her garage or somewhere it can be readily seen.
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I have seen all of these done over the years. Had a hand in many of them.