Jon, 44, had already eaten half the packed of Kettle Chips before making the revolting find.
The coffee shop owner, from Conwy, North Wales, bought the large bag from Sainsbury's, to split with wife Elinor.
Jon said: ‘I felt utterly disgusted when I saw it. It's such a horrifying discovery.
‘Me and Elinor had tucked into them completely unaware, and were just about to give them to my son for his packed lunch.
‘It's so gross and a real breach of food standards. I still feel sick and will never be eating a pack of crisps again.
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