Christopher´s tutor told him that all the teaching staff were expecting him to fail his exams. That was a real kick in the pants for him. From then on he started to take his studies seriously. EL-English Idioms
This was rectified to an extent by switching in the active circuitry, which gave the signal a kick in the pants, but care had to be exercised to avoid muddying-up the lower-mid frequencies and making the treble over-twangy. BNC
The discipline within the team let us down when we were put under pressure --; but perhaps it's the kick in the pants we needed,'; Jennings said. BNC