Scrubbing:   A highly advanced maneuver that you will rarely see performed except by the most talented young, energetic riders.  They use the face of a ramp to dissipate speed by just whacking the bars into a violent steering maneuver on the face of the ramp itself.  This dissipates energy rapidly and the bike leaves the ramp with a lot less "lift" and so less time is wasted flying around in the wild blue yonder when you really need to be on the ground with the rear wheel driving hard.  Problem is this explosive maneuver creates violent side forces that need to be disippated.  Again, the advanced rider lets the bike blow out sideways into a big whip and the stored energy drains away harmlessly (but the goal is achieved.  some speed is gone so the bike stays low off the ramp).