a piece of piss - A task so simple it's like you're peeing and your brain is o

A task so simple it's like you're peeing and your brain is on vacation.

That task was a piece of piss, I did it while eating a sandwich and watching the grass grow.

The job was a piece of piss, I finished it before my coffee was even hot.

I did that in 5 seconds, it was a piece of piss.