It means go f*** my orange. It's just like OMFG but backwards. It's an insult, really. In a way, like ktm - Kiss my teeth, or stfu - shut the f*** up. It's probrably the best insult ever invented because it overlaps every insults awesomeness.
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.