It bears some resemblance to the Kayak maneuver. There are invariably fluids deposited to the interior of the bag which are a minor annoyance, but which cannot be dealt with immediately. Often results in someone getting thrown out of the boat, much laughing and giggling by the participants, and jeers, applause and hoots by nearby campers.
Frequently performed by or with river guides, Climbing guides, etc.
John: "Yeah. I know. Everyone in the tent was laughing. I guess it was your turn."