Some things can't be unseen or deleted no matter how hard you try or what hacking technique you utilize. Once it's out there on the internet, once people have access to it, privacy officially turns into a myth. Plus, people can download it. Hence, even if you click on delete, your most haunting snaps will be there somewhere in someone's laptop as a treasure to be used later for trolling you.
Such are these snapchat fails. I don't know why they do really exist but they do and they are here to stay until you get your eyes on them and laugh your heart out.