"Have a black belt under the Nogueira brothers" is a phrase used when something is being handed to somebody for free or when you recieve something you haven't earned. For example a toy in Happy Meal.
Yes, I bought this car. I won a lottery yesterday so I got myself a black belt under the Nogueira brothers. (have a black belt under the Nogueira brothers)
A person (who in most cases isn't a martial artist) who makes condescending comments about a martial art but doesn't know enough about that martial art to know how stupid they sound.
"who needs karate when you can throw hands"
"its over when I see red"
"martial arts cant beat a gun"
"anime bullsh*t"
"that's not a martial art, that's jus roughhousing"
reply: don't be a Schrödinger's black belt.
When a martial arts practitioner holding the rank of black belt uses rank, in a social setting, in order to reach a more favorable outcome or get rights to something over someone of a lower rank.