The Transformers star had no idea what to expect when he signed up for the trip to the Grand Canyon with a pal, and will never forget the madness.
He says, "We hiked down and then they all dropped 'shrooms (hallucinogenics)... they started getting loud and crazy and it turned out like a Pink Floyd video. We sit there for a good half an hour (before we go).
"One guy sees Dracula in the wall, one guy's whistling Dixie and rapids are a team effort, so I'm looking around and feeling kinda nervous... I asked my friend, 'What's this rapid called?' and he says, 'Oh this, it's the Devil's Horns!'
"We get in the raft for a fraction of a second, the boat flips over... I keep inhaling... which is never good and I lose my water shoes... I wound up walking the rest of the river while they just tripped and floated by me."
LaBeouf insists he should have known the trip was a bad idea: "One, I'm Jewish... Jews don't go in rapids."