The act of cumming in the palm of the hand, and slurping it up like an oyster.
Semen in the palm of a hand resembles the inside of an oyster, which is also a salty viscous liquid.
A palm oyster can be carried out whenever an individual has no place to ejaculate, like a tissue or a condom, and is forced to eat their semen.
I was jerking off but didn't have any tissues so I had to eat a palm oyster.
"Me and my girl were having sex but we forgot the condom"
- "Did she eat your palm oyster?"
"Yeah man, slurped it all up"