My first year at elk camp Joe had a porta-potty in a tiny tent for the "facility"
As rookies, my brother and I had to dig the hole and empty the contents.
I vowed to never use nor be expected to dump that damn thing again.
I make my living at the dirty end of the cow, but human sewage is a whole different deal.
Renegade mentioned expressions from all over he learned in the military.
I learned one of them, your story reminded me of it. When someone is stretching the truth a bit, he's say
"That's richer than three feet up a bulls ass."