When you hold your shit in for so long that your body compacts it into the only known geological formation which can cut through a diamond. It is theorized that very center of the sun contains a small core of poop rock.
I once ate three square meals a day and yet did not take a crap for an entire week. That totals up to 21 meals without shitting. When I finally did, I excreted a perfect diamond. I have yet to attain a Poop Rock.