2 Chainz is calling for people to "pledge allegiance on one knee" -- in a direct response to Donald Trump ... and it's all part of a new song with NBA star Victor Oladipo.
The Indiana Pacers star just dropped his 2nd single called "Rope a Dope" (dude can really sing) -- and it features a rap verse from Tity Boi himself.
A rep tells TMZ Sports the song "serves as a response to President Donald Trump's attack on athletes who have been kneeling during the National Anthem.