In Super Smash Bros. Melee, the PC walk, or PC turnaround, is a sliding technique that involves transferring the momentum from a walk into a smash turn. The PC walk is named after the old-school smasher, PC Chris.
Performing the PC walk
Setting up a PC walk is similar to setting up a moonwalk by fast walking in the direction to slide and then transferring that momentum by turning, but is performed with a smash turn by quickly and lightly flicking the controller in the opposite direction instead of turning with a dashback by smash turning for more than one frame. This flicking motion is similar to a pivot, but whereas a pivot cancels the momentum from a dash, a PC turnaround transfers the momentum from a fast walk.
PC drop
The "PC drop" is the most common application of the PC Walk and is used to quickly grab ledge from a walk. It can also be buffered into a walk from the jumpsquat frames of a wavedash to quickly wavedash into a PC drop from further away from the ledge.