For instance, cereal boxes are meant to be opened on the end with the closey tab/slot thingie and I use it. But gum packs have little tab/tape thingies but I just pick a corner off and tear. Lindt giant chocolate bars have a tab on the back of the box but I just take the box apart. Canned bread has a tear and smack combo that I usually fuck up and just yank open with my fingers.
EDIT: canned bread - bread in a tube?