Um.... it’s when you spill something on your carpet and can’t come out...
Mum: Damn, I just spilled my noodles!
Me: WE’LL NOW YOU’VE MADE A FUCKING CARPET STAIN...
The Oroville Carpet Stain is where you blow a load in a girls hair and proceed to give her a nuggie, rubbing in the load.
After coitus, she begged for the Oroville Carpet Stain.