When the penis is removed from the oral cavity during fellatio and the recipient graciously ejaculates into one's own palm. The person providing fellatio is then slapped with the semen ladened palm, spreading the viscous emissions across the face. Generally considered a demeaning act.
He was delighted that his partner pulled out of his mouth prior to ejaculating until suddenly he found himself the recipient of a Seattle Slapjack.
by Truckdriver April 15, 2009