My Parents fitted a lock on my door a few years ago, so I don't have to worry about that one. The reason I had to have a lock fitted was because of my rather nosey Uncle, who seems to enjoy rooting through other people's bedrooms and personal belongings. He does have rather severe mental problems, so I can forgive him for that one.
If I didn't have a lock on my door, I'd have been caught about 100+ times by now, I think.