Ketchup packets
Don't ask me why, but ketchup packets used to fascinate me (okay, they kind of still do). Like, how do they get all the ketchup in there without making a big mess? Do they just clean it off afterwards? Do they use a tiny ketchup straw to get it in there? Or do they place a blob of the stuff on one piece of the foil-plasticy wrap, and then stamp another piece over top of it? (If you have any clue, please tell me, I really haven't the slightest idea.) And of course, you always get that one stubborn packet which just doesn't want to be opened. You try ripping along the dotted line, you try biting a hole in it, in a fit of desperation you even take a plastic knife from the silverware station and try stabbing the stubborn thing open. And then you give up (or at least I do, after all I've already spent five hours* trying and rubbed my hands raw making sure they're dry enough to open it) and toss it in the trash in disgust as you go for another one. Just like ketchup...