sacar el culo 45
It has several interpretations. One can be "withdraw", in this case there is a syncodoque where the ass represents the whole person and has versions like "carry the ass up. . . » by "move up (somewhere) " . Another variant may be "removing or flipping the face" of someone in a sign of contempt or any, of course in this case the 'ass' is an irony for "face". It can also be a little more literal and understood as "dodging the kick (by punishment, for expulsion).