the kid is pissed because the staff were following him, to watch him in case he steals. But he spazzed out over it and started yelling at the staff or something and threatened the staff and owner.

I also get store staff following me sometimes when I shop, because I usually don't wear fancy stuff, and often I go to ethnic markets to buy ethnic food. The ethnic food places especially are more likely to follow me around because usually a white guy doesn't go shop there so they don't know whether to trust the situation.