The carnival barker is a teenager who works at Super Silly Fun Land amusement park, running the "Space Killer" shooting gallery.  Like a lot of employees at the amusement park, he seems to find his job particularly boring, and alleviates that boredom by taking advantage of the kids who come to play the game, as well as their parents (or guardians).  He even tries to cheat on the kids who win, as he does when Margo, Edith and Agnes show up to play one day, hoping to win Agnes a huge fluffy unicorn plushie.  And he seems to succeed, all while thoroughly enjoying throwing some mean-spirited and sarcastic digs at the girls.  That is, until Gru decides to set the matter straight with one of his own guns...putting the young barker in his place, and destroying his game in the process.  And getting the fluffy unicorn plushie for Agnes...demonstrating his first touch of goodness.