2% is realer than any point in NFL history. Bills-Browns AFC Championship isn't that crazy at all. If Buffalo, Kansas City, and Cleveland all win this weekend (AKA no upsets), that sets up Browns-Ravens and Bills-Chiefs. Being in Buffalo and having already beaten the Chiefs this season, they would probably again be the favorites. So it would only take a Browns team upsetting a Ravens team, something they've already done once this season, and in Baltimore no less (though barely).
The Lions would need to take care of the Rams first (favorite), then they'd have to probably visit the Cowboys, where they were one misinformed eligible receiver away from winning in week 17.
None of that sounds particularly outlandish.