Sens

Paye-nous une tournée

Exemple

Tu ganhou no jogo, paga uma aí pra galera!

T'as gagné le pari, paye une tournée à tout le monde!

Origine

A transparent Northern Brazilian colloquial: paga uma [bebida] aí = 'pay for one [drink] over there.' No idiomatic origin beyond the literal request — typically called out in a bar after a win or a piece of good news.