Jet is a highly addictive chem that is commonly used by many wastelanders.
Background[]
See: Jet#Overview
Fallout TV series[]
In The End, a burly raider takes a puff of Jet when he fights against the Vault 33 dwellers there. The burly raider took a dose of Jet before attacking Chet, thereby causing him to die when Chet inadvertently closes the gate door on him.