When a person or group of people smoke(s) a massive amount of marijuana in one sitting.
Stoner 1: “Homie, my friend and I had a master sesh last night. We smoked a quad between the two of us.”
Master Sesh: define #2
the ultimate uninterruptable masturbation session
i locked the door, turned off the lights and threw on some quality internet porn. not even julius would be able to interrupt this mastersesh.