Nah yeah - A Kiwi thing where they say the opposite of what they mean,

A Kiwi thing where they say the opposite of what they mean, just because they’re weird and they think it sounds cool.

Nah yeah, I'm not gonna go to the party, but I'm gonna say I am.

Nah yeah, I don’t like this song, but I’m gonna say I do.

Nah yeah, I'm not gonna eat that, but I'm gonna say I will.