A silly Whitecloak did this to me once! Now the Faceplant holds emotional value to me whenever I play :3 Whenever I paused the game they would hit the snow and wait for me, and I always wondered if they were saying, "Are you back? Are you back yet? Are you back yet? Are you back? How about now? What about now? No? Okay. What about now?" They were so awesome ^-^
How do you faceplant? I had a journey once with a red cloaked partner that fell All the time; like if it was a quirk of theirs instead of just an a deliberate action. I tried to do it back but I couldn't! I felt like a jerk since I couldn't emulate what the other player is doing, and they were just doing it to make me laugh.
Well, basically what you do is you walk forward. Then, at a random point, move your thumb around EXTREMELY FAST in all directions. This'll put your Wayfarer off-balance, and thus make them fall. It takes about 5 seconds for them to faceplant fully. When you want them to stand up again, just make them walk forward and they'll stand up and shake the sand off their faces :3