In the lyrics of the song, "marked" could refer to being targeted or identified for something negative or harmful. In American English, expressions like "put a target on your back" or "have a bullseye on you" could convey a similar meaning. So, when the artist says "Might get marked for this but only common sense can make the strongest kid come in and martyr it," they are acknowledging that speaking out or taking a stand might attract negative attention or backlash, but it takes strength and common sense to persevere and face the consequences.
