So the NFC has won the coin toss for the past fourteen Super Bowls -- from the Super Bowl in 1998 to the Super Bowl in 2011.
That's pretty remarkable. I think this could perhaps be an interesting student project to investigate this in more detail.
One could probably find cases in history where magicians, gamblers, or con artists have found ways to manipulate coin tosses. Although that certainly wouldn't show that the Super Bowl coin toss was rigged.
If it was rigged one might ask: how was it done?
Barring any kind of vast conspiracy it is possible that the coin was rigged in such a way that it either always came up the same result or that it was more likely to come up a certain result.
However this approach is not consistent with the data. Although the NFC did win the coin toss for all of those fourteen years it was not always the NFC captain that called the result.
There were cases where the AFC captain called the result in the air but it landed opposite to that.