Folk song

[lusophile]

Hi there,

This is going to sound like a strange request but I'm trying to find the name of a traditional Portuguese song, which used to be performed by the folk dancers at Rocha Brava. All I know, is that somewhere in the chorus, the singer sings: "Ai sim, ai sim, ai nao nao - Ai sim, ai sim ai nao." twice. Whilst doing this the male and female dancers would stand opposite eachother and nod their heads in time to the music.

If anyone knows the name of this song, I would much appreciate it.