I know the shallow water blackout megathread has a bunch of info on passing out. Not sure on if passing out would work out ideally, I've heard you get knocked out cold from some and others say it's likely to wake up seconds after so do with that what you will. But to pass out you want to squat down and lean forward and take the biggest breaths in and out as fast as you can for a couple minutes, then stand up as fast as you can and put you thumb in your mouth and blow as hard as possible.