Soda that has been left out too long or is old, thus losing its carbon-dioxide infused goodness that we like to call fizz. It is not good. It makes people sad.
flat's best friend and synonym is warm.
Yeah, I opened it last night, so all there was for breakfast was flat coke.
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".