Also, you know what ? Listen to what I'm going to tell you, as in You know something? He's always hated spicy food , or You know what? They're not getting married after all . Both these colloquial expressions are shortenings (Of Do you know something? or Do you know what? ) and are used to emphasize the following statement or to introduce a surprising fact or comment. The first dates from the mid-1900s. The variant, from the late 1800s, should not be confused with what do you know or you know