Nah yeah - You're saying no, but you're also saying yes, but you don't

You're saying no, but you're also saying yes, but you don't know why, and you're trying to make it sound like you do, which is just annoying.

Nah yeah, I think I'm gonna win the lottery, but I also think I'm gonna die tomorrow.

Nah yeah, I might go to the movies, but I might also just stay home and eat chips.

Nah yeah, I like this song, but I also hate it, and I don't know why.