Black Mayonnaise noun
1. A toxic sludge found at the bottom of harbors, bays, and oceans - often extending for miles - consisting of undecayed sediment, sewage, and petrochemical waste.
First known occurrence, 1978 (The Atlantic).
2. A sludge/drone doom bedroom-in-an-apartment act, known for its brutal, torturous, haranguing, miserable, and absolutely crushing effects.
First known occurrence, 1991 (Ohio).
"The extreme to which Black Mayonnaise took the basic idea of heavy was ridiculous and I mean that as a compliment."

- Amelia (?)
House of Tinnitus

"Recommended for people who can only afford bad drugs or conspiracy theorists who know the 'real' story behind all those traffic light boxes that tell people when to stop and go."

- Scott Seward
Decibel Magazine

"The color is like lava, really black. It just kind of oozes. There is a stench associated with it. And it has the texture of thick mayonnaise, so it's very unpleasant stuff."

- Christos Tsiamis
Environmental Protection Agency