Bills lost to a CFL team....
https://profootballtalk.nbcsports.com/2012/06/23/nfl-cfl-teams-used-to-meet-in-the-preseason/
In the one and only AFL-CFL game, the Tiger-Cats took apart the Buffalo Bills in Hamilton, 38-21.
In the past 51 years, no NFL team (or AFL, during the league’s remaining years of existence) has ever again played a CFL team, in Canada or elsewhere. It’s unlikely that it will ever happen again. Still, every time you hear the name “Tiger-Cats” remember that they own the bragging rights over the Bills and, in turn, the league that absorbed the Buffalo franchise in 1970.