2 definitions by frat boi

when someone dresses like a 12 year old. examples of sixth grade syndrome are nike sneakers, track pants, and a t shirt.
Girls won't settle for guys who have sixth grade syndrome, we like guys who can dress themselves.
Mark looks like a twelve year old today, he must have sixth grade syndrome,
by frat boi September 26, 2017
when boys over the age of 13 only wear under armour sports perfomance t shirts, basket ball tshirts, and knock off yeezys. careful guys, its easy to contract this disease
Susan, you should never date a guy with sixth grade syndrome.
Nicholas Peter, you're 63 years old, stop dressing like your grand son!!!

Sean: "the under armour outlet mall has a huge sale going on! wanna go?"
Ben: "no because im not nerda af, and i dont suffer from sixth grade syndrome"
by frat boi September 27, 2017