An expression (traced to the skateboarding community of the early 1990's in Syracuse, NY) expressing the possession of particularly unattractive facial features.
Sam: Are you gonna call up that girl you met yesterday?
A-dog: Nah son, she had mad gas on the grill.
A-dog: Nah son, she had mad gas on the grill.
by word.smith May 29, 2008
Get the mad gas on the grillmug.