1) Let your wife and/or girlfriend drive your car.
2) Let her hit some invisible bumps.
3) Let her tell you what happened, her side of the story, and then wonder why the horn does not work when you turn on the alarm only to find out that the horn is missing.
Now you see that wasn't so hard now was it? Works everytime. At least for my wife.
Here's an extra lesson:
How to avoid invisible bumps.
Take the keys away from your wife and/or girlfriend.