We called it "kill the guy with the ball" - which sumed up the rules quite nicely. :)
A slab of playground gutterspout ice placed under your butt when going down the slide guarantees a mach 2 speed down the slide. After explaining it to my youngest daughter, she and the rest of the kids were banned from the practice last winter because the excessive speed sent kids flying out of control at the bottom of the slide.
When you're a kid, flying out of control is what you do best!