The key to breaking this potential advantage is to let someone other than the coin flipper call heads or tails while the coin is in the air.
That’s how I was taught to do it as a kid when we were playing for fun. I never really thought about the reasoning until now.
If you talk to people deep into the performance magic community, there are myths and legends of people who practice dice rolling to the point where they can influence the outcome of a dice roll. I suppose training for hours a day for years on end could have some such influence.
It is definitely doable. _Scarne on Dice_ (1945) details a number of methods for controlling dice throws. And Steve Forte's "Gambling Protection Series" videos show what the moves look like in action.
Mind you, none of these moves will fly in a modern casino.
As I recall, the techniques generally involve not making normal "fair" free-tumbling rolls, but constraining the die movements somehow. Things like tossing them into a corner or making one of the pair spin flat, around only a vertical axis.
That doesn't break the advantage, it just mitigates it. The advantage is just small enough that it doesn't matter much even before the mitigation. The caller could still look at the coin before it's flipped and have a slight edge in calling it.
It's not terribly hard to influence the outcome of a die roll. You can roll it end over end like a wheel so two of the faces remain on the sides and can't be the result.
There was an episode of the old "Breaking Vegas" series [1] on the History Channel about such "dice dominators". This site seems to have the episode online [2].
That’s how I was taught to do it as a kid when we were playing for fun. I never really thought about the reasoning until now.
If you talk to people deep into the performance magic community, there are myths and legends of people who practice dice rolling to the point where they can influence the outcome of a dice roll. I suppose training for hours a day for years on end could have some such influence.