Apple bobbing, also known as bobbing for apples, is a game often played on Halloween. The game is played by filling a tub or a large basin with water and putting apples in the water. Because apples are less dense than water, they will float at the surface. Players (usually children) then try to catch one with their teeth. Use of arms is not allowed, and often are tied behind the back to prevent cheating.
In Scotland, this may be called “dooking” (i.e., ducking). In northern England, the game is often called apple ducking or duck-apple.- taken from WIKIPEDIA