Interesting thing that happened to me; I saw a documentary on body language and thought it would be fun to test out some of what they were saying. The next day I was at the motorpool (Basically a big parking lot for all of my brigade's military vehicles) having a little conversation with a bunch of other privates and one sergeant, who was of course in charge and talking to us about what was going on.
After he gave us permission to not stand at parade rest (It's a rule that all soldiers below the rank of sergeant must stand at parade rest while talking to a sergeant), I decided to stand in a body position that communicated dominance. I put my hands on my hips with my elbows slightly forwards, and my head tilted slightly downwards, just like this-
I made sure to relax my face so there would be no facial cues. I wanted to make sure the ONLY thing I did was change what I was doing with my arms. The sergeant continued to talk, then about 20 seconds later he stopped, looked at me and said "I'm not scared of you". He said it in that "I'm going to laugh like I'm joking, but I'm totally not joking" sort of way.
I was taken aback, of course, and immediately said "Why would you be scared of me?" I was trying to play it off, even though he had reacted exactly like he was supposed to. Here was a Sergeant, supposedly in charge of the whole group, stopping what he was saying to react to a simple change in where my arms were and how I was standing.
It just goes to show how truly powerful body language can be.
By the way, he totally was scared of me.