The May 2nd Splendid Table included a segment on the history of Stadium Mustard in Cleveland, including explaining why there are two kinds, Stadium and Ballpark, and why one is sold at football games and the other at baseball games. I grew up knowing this as what mustard was, all that yellow stuff seemed strange to me when I first encountered it later in life.
Me? I fall firmly on the side of Authentic Stadium Mustard, and it seems half of Cleveland agrees with me. More about the mustard at All Things Cleveland, and at Chowhound. (Image from allthingsclevelandohio.blogspot.com.)