Country star Garth Brooks recently played 713 concerts in Pittsburgh* and in various performances wore Steelers, Penguins and Pirates jerseys. Brooks showed that he either really, really likes the Pittsburgh sports teams or he's just pandering to the crowd. I'm fine with either (though I hope it's the first one). If only he wore a Pittsburgh Spirit or Pittsburgh Maulers jersey. Anyway, here's proof of Brooks wearing jerseys including a video showing Steelers Coach Mike Tomlin ("a huge Garth Brooks fan") and Hall of Famers Mel Blount & Lynn Swann singing Brooks a Happy Birthday.
Brooks also took a picture with Steeler players Ben Roethlisberger, Cam Heyward, Brett Keisel & Matt Spaeth. (I think Shaun Suisham & Greg Warren are also in this.)
* This number may be incorrect.
Photos from Y108 & Cam Heyward's wife.