What's the story between them?
Think it goes back to 1977 where on the final day of the season Coventry or Sunderland could be relegated. Coventry needed to better Sunderlands result and Jimmy Hill who was a director at Coventry at the time delayed their kick off by 10 minutes due to heavy traffic, the Sunderland result then flashed up on the scoreboard which showed they'd lost to Everton 2-0. The Coventry game then turned into a bit of a friendly for the last 10 minutes and they got the draw they needed to stay up.
It went to the FA but Hill got off with it and now Sunderland hate Jimmy Hill and Coventry.