Bread is a term used to ridicule someone based off of their hair style and/or interests in furry fetish porn.
Person 1, "hey fuck you dude, you're a bitch (jesse pinkman reference)"
Person 2, "yeah shut up, bread"
Or,
Person 2, "what is uncooked toast called?"
Person 1, "fuck you dude"
Person 2, "oh yeah, haha its bread"