Welcome to the next great online debate: What are these people chanting?

I'm having flashbacks to dresses and "Laurel." There is a grand debate going on online over a clip that TikTok user Keegan Stiles posted on his account. In the clip, which can also be seen below, you hear a group of people chanting...something. It's a little garbled, and they're...British? Maybe? Regardless, it's hard to exactly [...]