Place a red near the corner pocket. The cue ball is trapped between the cushion and the black and located on the baulk line as shown.  The object is to pot the red, but the only way this is possible is play a push shot with slight screw, obliquely squeezing the cue ball into the cushion, although slightly devious this shot is very impressive from a snookered position. Takes a few trial and error attempts, to get the right angle of the cue to the cushion.