Druggie porn is any picture of any mind-altering substance of a particularly large amount or good quality.
Could also be a movie or book portraying the injesting of such drugs, such as Requiem for a Dream or Fear and Loathing in Las Vegas.
Bob: So Jon does coke now...
Suzy: How do you know?
Bob: He was looking at druggie porn on his phone.
Jackie: These are the most gorgeous shrooms I've ever seen...lemme take a picture, I want some druggie porn for reddit.