Definitions by mogwai666

Slender man's brother 

The man that stands in the background of a porno and does not participate in the sex.

Kid 1: "I was watching a porno last night, and happened to notice this creepy guy just sitting in the background watching.."
Kid 2: "Oh yeah, we call those guys Slender man's Brother, I dont know what the deal is with those guys."

Slender man's brother by mogwai666 December 27, 2011