I am writing a poem for school. The verse with the word I need to change is this:

7 hours is too long
In much too short a day
You really don’t care if you get an answer wrong
Because you don’t care a _____ about radioactive decay

The only thing I can think of is the word shit. Do any of you have an idea for a more clean alternative?

I have tried shiznit and shoot (which most websites suggested as alternatives), but they don't sound great.