Yeah, a panic button or alarm might scare them. My brother in law was sitting in his car while my sister (his wife) was in the grocery store. A convertible parked next to him and opened her car door hitting his pretty hard. He told her to be careful but she was rude that even if it made a mark, noone would notice.
When his wife came out, he took the eggs from her and start to crack, then empty egg yolks all over this witches car! I just wish I could have seen it! lol