v. 1.Fladunking from a high altitude. 2.To strike a person's face, as if fladunking, but with great animosity and vengeance.
n. The harsh thwapping of a male's genitalia against an unsuspecting and/or deserving recipient's supple face.
See also: fladunk
"Johnny pounced from atop his pine dresser and gunderthumped Mary in the noggin." - Beauty and the Beast
"Reverend James performed a severe gunderthumping to chastise Billy, the sinful choir boy. However Billy bled and later suffered severe and unrecoverable head trauma" - NY Post 7/31/89
"GUNDERTHUMP!" - Voltaire