The most sophisticated way of expressing a mind fuck on instant messaging. Expressed after viewing something that just makes you go "heiucrwy89lq39rlqtvy8huidhjszfaiuehwu9lhjktvu4 hq3atw8bhvj,2qioy78" or similar. Mostly expressed after viewing such things as 2girls1cup or goatse.
Keyboardmash (ing) is a style of typing employed by the larger public, it is equivalent to the result of most people opening their mouths. To keyboard mash you simply hit random keys in rapid succesion.