Crumpet packets. Seriously why are they made so they are so difficult to get into?
Add to that the little packets of three that Jacobs Crackers come in these days.
Now I appreciate the improvement over the old days when having opened the cracker box, the ones you didn't use would inevitably go stale after a few days and at least these little packets of three they seem to come in now prevents that, but, it seems impossible to open them now without breaking at least one cracker in the process.
The only way I've found to get them out without breakage is to turn the packet of three on their edge and use a sharp knife to then slit the cellophane wrapper open in order to retrieve the contents intact.
I say cellophane, though I suspect it's related to the sort of stuff also used in bulletproof vests or even Chobham type armour for tanks.