[TimesOldRoman]

Even that poses a fun test. What flipping method is needed to ensure some level of randomness.

I love that idea of a grifter being able to flip a coin as they choose.

[faheel]

Maybe letting the coin fall on a hard surface, so that it has a chance to bounce/spin randomly before falling flat (or staying on its side!)

[MisterBastahrd]

Probably a device that would uniformly toss the coin with regards to force applied at X number of different strengths.

[ChadNauseam]

Or have both people flip a coin secretly, then reveal the coins and XOR the results :D