To block someone from hitting more marijuana, usually mid-rotation on a piece or bleezy or spliff. Similiar to a cockblock.
Ronald was about to take his hit
Zackary says, "No I think you have had enough man." and sticks his hand in front of the piece, blunt, spliff.
When one is about to smoke some pot and something happens to keep you from doing so.
Johnny was just about to light his joint when his mom walked into his room with the DEA. What a pot block.
One who prevents another from smoking marijuana, either at a party or in an informal situation.
I wasn't able to get high last night because Kim was a potblock
A mental block instigated once sober on imagined and creative ideas/visions conceived or envisioned whilst high.
Guy 1: "Dude, I had a bitchin' idea for creating world peace toking yesterday."
Guy 2: "What was it?"
Guy 1: "Can't remember, totally potblocked ."