As the name suggests, "Holy Shit On A Shingle In The American President's Dick!," Is used to describe a holy piece of shit, blessed by a hooker, stuck on a shingle that was shoved up the American President's Dick hole, with the piece of shit still on the shingle.
When you fail at something in life (eg. failing an exam or not getting a job), go home and spend an hour just standing in the shower, propping yourself up against the wall with your eyes on your feet.
Caleb knew the only thing to do after he didnt get prefect was take a failure shower.