A beard slap is the slapping of another person with large amounts of concussive force, resulting in the formation of a beard. It is both the worst and best thing you could do for a person.
Person 1: "You are completely wrong I couldn't disagr-"
Person 2: -BEARD SLAP-
Person 1: "...Actually..."
Person 2: -BEARD SLAP-
Person 1: "...Actually..."
by KEEXNAN November 07, 2008