I'm going to get in a fight with a 7/11 employee
That sounds pretty violent. Why do you want to fight the employee?
I wanted to steal his food, but he wouldn't let me.
He shouldn't have let you steal the food. No one would want their food stolen. If you try to act violently toward him, though, that will make the situation much worse and you could be arrested for assault.
I'm going to tell him you are the police since cops are pigs.
It doesn't really matter what you think of the police, it's not right to steal from people. You shouldn't bother people who are trying to just do their job.