We’ve all had moments with our friends that leave us laughing like hyenas for no discernable reason — one person laughs, another person laughs at that person, those two stop and a third starts, ad infinitum. But I’ve never experienced this phenomenon via YouTube video. Here’s a bunch of metroriders in Berlin laughing their asses off. There’s something hilarious and relatable about this video, after you get over the initial desire to scream “WHAT THE HELL IS SO FUNNY?” at your computer screen. I dare you to watch this video all the way through without cracking a smile. YOU CAN’T DO IT.