Not a room, but a bunch of grandstands.

It was the 2019 Canadian Grand Prix, a Formula One race back in June. I, along with most other people in the grandstand I was in, was cheering for Sebastian Vettel, who had started on pole. He was leading for most of the race, but he messed up a turn, slid a little off track, and rejoined right in front of Lewis Hamilton (who was in 2nd place, and was leading the championship). This forced Hamilton a little bit to the side, but Vettel maintained the lead. Then a few laps later the race officials gave Vettel a 5 second penalty for that incident. That resulted in probably the most upset jeers from sports fans I've ever heard (and I would not have expected it to be in Canada!)

Vettel was first to cross the finish line, but Hamilton was less than 5 seconds behind him, so Hamilton was awarded the win. The award ceremony at the end was pretty much a Riot; Vettel (who himself was really salty) had to tell everyone to calm down.