muffler lip 

Someone who smokes very heavilly - usually has very bad breath.

Their diet of coffee and cigarettes gave them a nasty case of muffler lip.

muffler lip by Matt Plank September 29, 2006

Muffler lips 

The result of smoking rocks and incurring 1st, 2nd, and/or 3rd degree burns on your lips; as if they've been placed on a hot muffler.

Crackhead Sally got muffler lips.

Muffler lips by WithaZ December 24, 2018