For real. It's called Power Posing.
Have a tough test you need to ace? An important job interview coming up? Meeting the parents?Standing like a Superhero for as little as two minutes changes our testosterone and cortisol levels, increases our appetite for risk, causes us to perform better in job interviews, and generally configures our brains to cope well in stressful situations
See the whole article here: http://blog.ted.com/2012/10/01/10-examples-of-how-power-posing-can-work-to-boost-your-confidence/