I think I was 9 or 10 and my friend and I were home alone at his house while his parents went out to dinner. After about an hour of playing video games we go to get food and the house alarm gets triggered and we were both fully convinced someone had broken into to the house with a weapon to rob the place. We hide underneath bean bag chairs for at least 30 minutes before I worked up the courage to run and grab the home phone a few rooms away. Called the cops and they came and searched the house and didn't find any sign of a break in. I'm pretty sure his parents just accidentally set the alarm and we triggered the motion sensors. Scariest thing I can remember aside from getting robbed at gunpoint