Some unknown guy punched Brendan. Brendan appeared before V.P Trueman.
V.P Trueman: So you didn't know this boy?
Brendan: No sir, never seen him.
V.P Trueman: And he just hit you?
Brendan:Like I said, he asked for my lunch money first. Good thing I brown-bagged it.
In google, Brown-Bagged is related to sex, but here context is so different.