Boy at work stuffs his face with crisps, cakes, biscuits chocolates, monster munch all day long?

His jaw is forever going. He never has any 'healthy' food and has them all for breakfast, lunch, etc. His packets rustle all day long and it's irritating.
Is this normal behaviour? I've never seen anyone like him in an office before. He'll go through a box of mini donuts too.
Update: So does your answer, Anon.
Update 2: Yes, the whole office has already said that to him, Patricia.
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