Boat setup
Surf side
The side of the wake, regular or goofy, that the boat is set up to surf, selectable on modern boats at the push of a button.
The surf side is whichever side of the wake the boat is configured to produce a clean surf wave on. Setup, through list, ballast bias, and the surf system, makes one side steep and rideable while the other side is washed out. Modern surf systems let the crew flip the surf side from regular (left) to goofy (right) instantly so riders of either stance, or riders trading off, can each get their preferred side.
Matching the surf side to a rider's stance (regular vs goofy) lets them ride frontside, facing the wave, which is generally easier and more natural.