A rare form of male masturbation involving a window sill and a feather. One places their johnson onto the window sill next to an open window, takes hold of the window, and slams it down onto their member; the mash. Then, one runs a feather along the side and head of their jimmy; the tingle. This form of masturbation is not advisable, and requires a window that opens vertically.
by Danno Chuchiak April 11, 2007