Onomatopoeic word often seen in foreign language graphic novels and cartoons to indicate when something has been plugged.
"...as the huge African transsexual lined up his thick tool with Maverick74's winking anus, the trashed browneye quivered in anticipation of yet another violent reaming. As the straddling nubian bore down on his prey the sphincter gave way with a dull 'STUMPFF!"
by The Drizzla! March 19, 2007