Lil Wayne is referencing his status as a Blood Gang Member, who traditionally carry red rags in their pockets. "On the rag" is a slang expression for a female on her period so they would have a bloody rag (tampon).
This rapper, just by going into the recording "booth" and spitting a rhyme will teacher rappers how to rap, much like a coach. John Gruden is a football coach who was fired and became a TV commentator on football games, therefore he is the "booth".
His lady friend is very loud during sex so she brings the racket by making a lot of noise as Venus and Serena Williams do when they score points in tennis. Simultaneously a reference to a tennis racket.