The person flipping the coin has a significantly higher chance to calling the outcome. Stack the odds in your favour by volunteering to be the flipper.
Wired's How-To Wiki highlights the findings of researchers at the University of British Columbia and how you can take advantage of being the coin flipper.
The trick is to practise flipping the coin enough that, like a knife thrower, you become in tune with how many rotations it takes to get the side of the coin you want. The resident doctors used in the study were given five minutes of coaching and some pointers and they raised their chances of getting the coin face they wanted to 68 per cent — a significant leap over chance for a mere five minutes of practice.
Check out the full wiki entry at the link below for addition tips and trick including how to stack the odds in your favour when you're not the coin flipper.
Win a Coin Toss [Wired]