Many people have flipped coins but few have stopped to ponder the statistical and physical intricacies of the process. We collected 350,757 coin flips to test the counterintuitive prediction from a physics model of human coin tossing developed by Diaconis, Holmes, and Montgomery (DHM; 2007). The model asserts that when people flip an ordinary coin, it tends to land on the same side it started. Our data support this prediction: the coins landed on the same side more often than not, Pr⁡(same side)=0.508, 95% credible interval (CI) [0.506, 0.509], BFsame‐side bias=2359. Furthermore, the data revealed considerable between-people variation in the degree of this same-side bias. Our data also confirmed the generic prediction that when people flip an ordinary coin—with the initial side-up randomly determined—it is equally likely to land heads or tails:Pr⁡(heads)=0.500, 95% CI [0.498, 0.502], BFheads‐tails bias=0.182. Additional analyses revealed that the within-people same-side bias decreased as more coins were flipped, an effect that is consistent with the possibility that practice makes people flip coins in a less wobbly fashion. Our data therefore provide strong evidence that when some (but not all) people flip a fair coin, it tends to land on the same side it started. Supplementary materials for this article are available online, including a standardized description of the materials available for reproducing the work.