Sometimes, you're just fresh out of snowboards and you've got to use what resources you have. In Norwegian Olympic slopestyle and big air snowboarder Stale Sandbech's case, it was human beings. So he grabbed whoever was closest—in this case, fellow Olympian, slopestyler, and big air-er Tyler Nicholson from Canada—and rode him like a slab of wood down an Olympic-groomed mountain.
In case you wanted to get another look at their technique:
Human snowboarding seems like the next wave. Hell, it's not like the two-man luge is all that different. It's just that the whole waxing part might hurt, though.