Delivering a 16-bar verse without “punching in” vocals.
He may also be referring to punchline-oriented lyricism (or “hashtag rap”) that a lot of mainstream artists like Lil Wayne rely on.
Or it could be a double entendre as well. “Punch” not only means “punching in” vocals, but can also refer to “punch” drink that many kids drink for school lunch.
Example:
