When one swipes one's hand across something in an unintendedly haphazard and inappropriate fashion such that parallels could be drawn with the actions of the mentally deficient.
Adam was playing backgammon with Anthony and he rolled a double five. He mongswiped four checkers five points across instead of moving them individually and his mongswipe caused his hand to ricochet off of Anthony's checkers such that their previous position was no longer to be determined causing quite the furore.
by 78offtilt November 10, 2010