a kick up the arse

a kick up the arse/backside

  (British & Australian very informal)
if you give someone a kick up the backside, you do or say something to try to stop them being lazy He does nothing but watch TV all day. His mother should give him a kick up the backside. The threat of losing my job was the kick in the pants I needed.
See also: arse, kick, up
References in periodicals archive ?
It is not a great start to the European Championship campaign and we have had a kick up the arse.