Coffin varnish 

Alcohol, especially moonshine

He gave me some of that homemade coffin varnish he drinks. I couldn’t. I had to spit it out into the sink.

Coffin varnish by Dawn Chorus May 4, 2020

coffin varnish 

Very strong coffee, especially coffee brewed with Dr. Pepper, caffeinated water, or yesterday's coffee instead of normal tap water. Features may include an oily sheen, a strong chemical aftertaste, some form of cheap alcohol mixed in, or a horrible sense of impending doom after consumption.

I drank coffin varnish to stay awake all through finals week, and now I'm afraid to fall asleep because the walls are breathing.

coffin varnish by rumpuskat July 30, 2009