A bunch of rich white people paying $250/mo. to have an uncredentialed coach instruct them to have spasms with PVC pipe and siezures on pull-up bars until they vomit. They generally do this for a period of 10-30 minutes and call it a workout. Those who partake in these group activities also have the option to pay $1000 to attend a weekend course where they have an alcoholic instruct them how to better lift their PVC pipe. Some people who do these activities may also confuse being nauseous with being elite.
Guy 1: Hey, I started this great workout program lately. It's called CrossFit!
Guy 2: You go have fun with that. And don't bother calling me when you need someone to take you to the emergency room.
Guy 3: Dude, when did you get all those tribal tats? You didn't start---
Guy 4: Hey man, I just started doing this awesome workout program called CrossFit!
Guy 3: Oh, fuck.
Guy 5: The CrossFit workout was brutal today! I'm already sore as hell!
Guy 6: Maybe you should have scaled down to 1/2" PVC rather than 3/4".