Rio Grande do Sul,
The term is known as the unofficial currency of the state of Rio Grande do Sul, but it has also spread to other places in Brazil. It can be used interchangeably with the official currency ("Real") in every informal situation.
The term started tu be used in the 1930's when the friends of the exiled politician Raul Pilla started selling bills of money (as financial bonds) with Pilla's face on it to raise money for him.
"Coitado do Raul Pilla, foi exilado sem ter nenhum pila no bolso..."
"Tu não tem uns pilas aí pra me emprestar?"
"Não acredito que encontrei 50 pila no chão!"
"Poor Raul Pilla, he was exilled without any pila in the pocket..."
"Don't you have some pilas to lend me?"
"I can't believe I found 50 pila on the floor!"