This one's a bit old, but I still like it. Cohen is one of the greatest trolls of all time.
The thing is, when Cohen does one of these song based trolling attempts, it's hard to tell whether the people singing along are doing it because they agree with what's being said, or just because it's catchy.
I know that. He's dressed in a pretty over the top costume, so they could have easily realized it was a joke and went along with it anyway. It was obvious when people were doing this in some of his other trolls. You just don't see the full crowd here.