Two cash-strapped women got into a nuclear argument that ended in a ferocious slap ... outside Mastro's in Beverly Hills.
Here's the way it looks. The 2 girls are dressed in their best and possibly only real fancy get-ups ... one carrying a Louis Vuitton bag -- or a counterfeit ... we can't tell.
An argument erupts almost immediately ... because one of the girls apparently had a drink at the bar but didn't have any money to cover it, so they dined and dashed. A Mastro's employee confronted them outside and the girl's friend had to pay the $20 tab.
It's so entertaining ... a high heel breaks, they trade tirades, there's slapping ... it's got it all.