a bad or unenjoyable thing, event, or smell; derived from the powdery film left under your fingernail after having scratched the upper part of your buttcrack and not having showered for a while.
"Man, that last game of Mario Kart was poo-poo cheese! I only got hit with red shells the whole time!"
or
"Oh my god, that smells like absolute poo-poo cheese."
or
"I'm playing insert game here like ass today."
"Yeah man, you're poo-poo cheese right now."