The state of being so high that one's short-term memory is unable to function, referring to the condition of the main character in the film Memento. This condition can lead one to write notes or write on their body to remember things like in Memento.
Stoner 1: Dude where are we?
Stoner 2: I don't know, I'm Memento High right now.
Stoner 1: Shit me too.
Stoner 2: Don't worry. I left myself notes.