Answer:
I would have a talk with him.
Explanation:I would take him outside and say " I think this is very unfair that you somehow find a way to sneak into the kitchen and get the job I have wanted and have been working extremely hard for and i think either you work things out with our boss or i will and if you don't then i will get you fired because i have seen you sneak into work late every day and i have not said a single word to anybody and if aanythingyou owe me your job now go confess to boss or i'll get you fired"