Slang used here and there by Some people
It comes from the possibility to call companies customer service in Brazil using the prefix 0800 without being charged for it.
"Vamos à festa na sexta-feira, a entrada vai ser 0800."
"Lets go to the party on Friday, the entrance will be for free."
Added May 2020 by amipedro
5 out of 16 Portuguese speakers have heard this