Definitions by Master Tricon

Diesel grin 

Having a noticeably poor mouth hygiene to the point of blackened and/or rotting teeth, associated to damaging activity like siphoning gasoline from a vehicle or hard drug abuse. See also Meth mouth.

Hey bro, that girls checking you out.
There ain’t no way I’m going near that diesel grin!

Diesel grin by Master Tricon September 17, 2025