Ok, this actually happened to me a few minutes ago so that's why I'm writing it now. It isn't really necessary, at all. I was in the downstairs bathroom, and as I went in I was about to shut the door when I did, it was slightly open but I hadn't really noticed it. I was getting up, when the door locked itself, unexpectedly. I felt my heart pounding already, I was even shaking a little bit. I tried really hard to kick it open, shove it open and run into it, but nothing worked. I ended up going through the vent, we were lucky to even have one otherwise I would've been stuck in there for the next 3 hours, as it was 6am and I was the only person awake. I did hear some whistling sounds while crawling through the dusty but clean vent. As I climbed out, I slid into the living room, where I saw my brother sat on the couch, about to watch the weather. When he saw a glimpse of me, he immediately asked me what I was doing up there and why, I explained everything. Even though he did believe me, and made the door more secure, I promised myself I'd never put a foot in there ever again.