Here is a quick history lesson for ya'll:
Dap is a form of handshake that became popularized in the white mainstream society in the 1960s originating among African Americans. The term dap may have originated as an acronym for Dignity and Pride, (or may have been backronymed) and was popularly used by African American soldiers during the Vietnam War even though as a tradition it has existed in the African-American community for centuries. Though it can refer to many kinds of greeting involving hand contact, dap is best known as a complicated routine of shakes, slaps, snaps, and other contact that must be known completely by both parties involved, otherwise, an awkward but friendly improvisation occurs as the participants essentially mirror the jazz culture with creative forms of ordering the various moves of the hands with snaps, slaps, mutual knuckle bumps and finger waves (jazz hands). Some forms or other names for these greetings include “slapping five,” “Black Power Handshake,” “high five,” “Five on the Black Hand Side,” and “the pound”. It is often confused with the word “tap". The dap may be derived from West African non-verbal traditions brought over with the enslaved Africans to the Americas starting in the 1600s. It is a ritualized but common form of agreement between two or more people who offer this casual physical contact as an affirmation, congratulations or other type of agreement with an action, clever phrase, sports event or when admiring an attractive female or male."