When you fart into a mug that has been frozen. The heat of the juicy fart will get sucked into the frozen mug, causing the fart to liquefy into a bubbling stew. This is when you then tilt mug (as if taking a drink) and suckle the "Aroma au jus".
"To take care of this hangover I think I might have a "Rusty Mug."
by SSDRD September 20, 2008