Someone who is a piece of crap. A boogie (or booger), comes out of your nose. Crap comes out your ass. So it's basically saying that you're a piece of crap if you're an assboogie.
Don't listen to them, they're all assboogies anyway!
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".
I don't buy the schmegegge about Morty sleeping with Moira.
His version of the story was pure schmegegge.
The whole schmegegge was made up to get Liz a little bit of attention.