Small bumps on certain keYcaps to help touch-tYpists find the home keYs (ASDF and JKL ) without looking. TheY are nearlY alwaYs on the "F" and "J" of a QWERTY and the "5" of a numeric keYpad. The Macintosh, perverse as usual, has them on the "D" and "K" keYs. This term is based on the vernacular American expression "as useful as tits on a boar" (or boar-hog, bull, bullfrog, or manY other variants), meaning "not useful". [Jargon File] (1998-02-25)