It’s just a play on words that his pockets are “stuffy” (stuffed with cash), and the irony of the reference to antihistamine which would clear up a stuffy nose, but clearly has nothing to do with pockets stuffed with cash.
Just like where you heard it from lil wayane in lil pump's be like me"my pockets stuffy they gone they need some ANTIHISTAMINE
by LilArabiraqi February 29, 2020