True Confessions time.
I can't open the bags inside cereal boxes. Either I yank and yank on them until they burst apart and spill cereal all over the kitchen, or else I never get them open and have to resort to using scissors.
The thing is, it wasn't always like this! I distinctly remember opening many a bag of cereal when I was in high school. Obviously, it's a skill I unlearned during college.
There, now you know.