Sleep and dreaming guru Robert Waggoner has speculated about the possibility of mutual lucid dreaming. For instance, he envisions two snoring individuals hooking up in dreamland for a cup of decaf coffee. MMA had another perfect test case recently, but something went wrong.
Dalton Holverson and Alydn Ashcraft connect with simultaneous right hands in this video from The Clash 11 on August 23, 2014. Both men enter dreamland at the same exact time. Their disconnected egos meet for a brief moment of shared defeat. But as the referee rushes in, Dalton violates their unconscious agreement. Sneakily, he wakes up.
The lesson here is that if you can spring back to life the second before the referee calls a double KO, you get to win. I would suggest that everyone starts training consciousness recovery, training with a guy who enjoys green-lighting people four or five times a sparring round. But that seems unsafe in the long run.