Pricking holes in the rolled-out pie dough allows the steam to escape while it's baking. Without this, the steam would puff up in bubbles and pockets throughout the crust, which would make some parts of the crust cook too quickly and also result in an uneven surface for your filling. Docking is simple. Just roll out your pie dough and lift it into the pan. After pressing it in and shaping the edge, prick it all over with a fork.