You tend to say this when you've probably just started to spend more than you can afford on a night out. But fuck it, you only live once, you're at the bar, hand over that card, that 'dollar and you're like
"Money Flow!!"
*Nightclub, music is poundin', at the bar*
Bartender: *raises eyebrows at you*
You: "20 shots of vodka!"
Your friend: "Dude, wtf, how much money you got?"
You: "Money Flow!!"