Pretty much means anything you want it to. Your teacher randomly gives you a pop quiz? You got memed on. You accidentally go left instead of right? Memed on. Originated solely because I started to say “get dabbed on” unironically, so I needed to think of something worse than that.
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".