Boof is a technical term in the sport of whitewater kayaking. What it mean is to use a rock (called a boof rock)to launch your boat flatly of of a small waterfall. This way a kayak lands beyond the hydraulic off of the bottom of the waterfall or avoids rocks that they would otherwise land on. Boof strokes refer to the stroke someone takes when making a boof move.
He totally missed the boof line and got pretty banged up.
To boof gorilla falls, hit the little rock three feet from the left wall.