A "perfect storm"
When you take the worst poop of your life and then wipe only to find out the toilet paper is completely useless.
'I pooped so bad, and the toilet paper was blank. That was a perfect storm.'
'I had a poop so bad, I needed five wipes and the paper was blank. A perfect storm.'
'I sat on the toilet for 10 minutes, wiped, and the paper was blank. A perfect storm.'