One who has sex with their daughter, and fathers a son. The father would be a dad, and a pap, thus a dadpap.

This can also be used as an insult, because sleeping with your daughter isn't exactly good.
Aden slept with his daughter Tara and had a baby named Matt. Aden was Matt's dadpap.

Matt you dadpap, quit hogging the game!
by RobertLynn June 4, 2006
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