The act of one being pompous, bitchy, harsh, or unreasonable while the target individual is in a good mood and mellowed out (in most cases the usage of herb is involved).
A guy walks by and says to you "you are a wuss and I know you can't pull off that trick on your skateboard". Your response is "that dude just did some major harshing on my mellow".
Generally playing the "Devil's Advocate" when I'm trying to make a point, or irritating me into answering a question, or giving me a hard time when uncalled for.
"I was trying to eat my chalupa when this bitch came up and got up in my face about how I should be vegetarian or some shit, so I told her to quit harshing on my bus."
Someone who is addicted to obtaining money and building wealth. A money addict and fanatic. Breadheads often work more than one full-time job, and some even participate in illicit activities to "obtain the bread".