When someone are dabbing the wrong way, you can either say "Facepalm dab" or just do the "Facepalm dab" - slap yourself in the face while dabbing.
Person 1: *tries to dab*
Person 2: What was that?
Person 1: A dab
Person 2: No, it was a Facepalm dab *while doing the facepalm dab"
Person 2: What was that?
Person 1: A dab
Person 2: No, it was a Facepalm dab *while doing the facepalm dab"
by DeadlineMaestro February 23, 2017