Taking screen shots/posting on own?

[AC Question]

I woke up this morning, grabbed my phone, and saw it had taken a screen shot....I looked at it and it was of a Facebook messager convo THAT I DIDN'T HAVE! It was a series of random things I sent to a person I hadn't even been talking to! I went to delete the screen shot, and there were a ton more. I then looked at the screen shot album, and there were over 4000!!!!! There were also random posts in a thread from me. Like a couple letters in each post. I was totally asleep when all this happened. My phone was plugged in, face down on my nightstand like it is every night.

How in the world did the happen?! ?!?!

 

[B. Diddy]

Welcome to Android Central! Which phone? Does it have any other methods of taking a screenshot besides the usual Power + Vol Down button combination?