a good flash mob for once

I was watching a fight when a hockey game broke out.

So goes the old joke. Flash mobs are somewhat similar, although I'd say most of them fall into the category of obnoxious performance art. But every now and again, you'll get a group of people of good will and a song in their heart, resulting in things like this:

I know there are crabby assholes who don't want their lunch interrupted this way, and while I can't blame someone for being caught while in a foul mood, I think you'd have to have a heart of stone not to enjoy such an exuberant, spontaneous performance.

Note: this video was posted 3 years ago.