What is Nah Nah?
1.
Nah Nah is a term used when someone is annoying you by being silly and making stupid, and not sensible comments.
When your boyfriend keeps telling you he loves you after 3 days, and won't stop. They are a Nah Nah
See
2.
A phrase said to show opposition. Usually said by people who are nicknamed "the gooch."
Does vinny get a lot of girls? NAH NAH
See