This morning, dh opened a brand new box of Rice Krispies (coincidentally purchased from Tesco) and discovered the inner bag was slit open. It was, I admit, quite odd the way it was slit, ie not along the seam of the packet but at right angles to it. BUT there was no damage to the box and nothing to account for why the inner packet was slit.
Anyway, dh was unhappy about it and wouldn't eat any of the contents. As no-one else eats them in this house, I am obliged to throw away a full packet of Rice Krispies. I think dh was worrying that they had in some way been tampered with I tried a couple and they were crisp and I have not died of Polonium poisoning yet... but the point is, what would you have done in that situation?