When a girl is giving a terrible blow job and the guy whips his dick out and hits her across the face. This contact will leave a mark. This usually occurs when a girl has braces and is scatching a man's penis in the process of a blow job
The reason why Jennifer Aniston didnt show up to the Academy Awards is being the night before she got fadonked and had a mark that resembled my penis.
by TittyFuckHerAss March 03, 2009
1 more definition
to smack ones nutsack or cock against another person's face
while mary was sleeping i fadonked her
by david kain February 28, 2007