The substance of one's nose slurped out of one's fingernails, ideally a big ole booger jellied in white mucus (the oyster) slurped from the tips of one's French-manicured fingernails (the oyster's shell)
Brett: You digging your nose?? Disgusting!!!
Katie: The oyster of the little man, for you my poor hobo. Try it.
Brett (slurping Katie's mucus-y booger out of her French-manicured fingernail): Yummy! Just have the Tabasco sauce ready next time.