A bag of potato chips has an opening/chip; after tearing (something??) off the bag with the aid of this opening, something [SOMEONE???] throws 'that part' onto the floor/ground and walks on enjoying his potato chips.
I think that the potato chip bags where you live are designed differently than what the respondents so far are used to, WB.
Let me try to describe what I believe a bag is like. I'm not sure I am right on this. Can you provide a picture?
There is an opening in the bag that is covered with a glued on/sealed on cover. A person can peel this back or peel it right off.
If I am right, it could be called a zip strip.