A predecessor to the "mung barnacle", the goog oyster is a relatively large, moist, collection of shmutz found at the corners of the mouth. The "goog oyster" is usually found on ones mouth after excessive narcotic consumption, an extensive conversation with greg, or caused by excessive dairy consumption.

A condition of the post coital female vagina whereby it is rendered cum filled and oozing ejaculate down to the ass crack. Oyster Slick vaginas are great for cream pie lovers and those that love sloppy seconds and thirds or more, especially in a gang bang session.

when ur balls get super fuckin sweaty and your cock gets stuck between em and then you just hafta pry it out that's a dickoyster

Vagina; Possibly inspired by the alleged resmblance between a pussy and an oyster. This term, along with several others, was popularized by the Bloodhound Gang song, "Foxtrot Uniform Charlie Kilo" (F-U-C-K in Phoenetics).
*Not a term one would use in serious conversation

a semi-solid ball of phlegm one coughs up

Noun. The kind of huge, vile, cancerous-looking greeny coughed up and spat out onto the ground by British Naval dockyard workers. Called an oyster because of the solid, greeny, snotty, rubbery centre surrounded by a lighter, watery fringe of phlegm, and the fact they just CLING and stick around for ages. British sailors have inventive imaginations, so you couldn't expect this to go un-named for long.