This thread seems pretty jacked up. If you want to keep the picture that someone is sending you, have them text it to you or send it on facebook or something. If you don't want to ask them to do that, or if they don't want to do that, then you know that you shouldn't be trying to keep whatever picture they're sending you.Quit trying to take advantage of people, dude.
Okay... This seems to be blown way out of proportion. The original poster asked how to screenshot a snapchat (which is a feature most current smartphones can do). He/She did not ask to be judged or to be told that this is not right. In your mind, you probably are thinking about nude pictures or unattractive pictures of someone. If the thread maker is anything like me, this is for comedic purposes and solely for fun. Some Snaps deserve to be viewed forever or at least by you whenever you feel like it - it's that funny or meaningful. If someone sends a nude, then the person who screenshots is not at fault, the person sending the nudes out are exposing themselves. Once you put it out there, it's out and you must suffer any consquences. I used to be able to screenshot snapchats by using Home + Power/Lock button, but with an updated version of my phone I no longer cannot.
Back to the topic: I can screenshot Snapchats by using the Volume Down + Home button, I have tried Volume Up + Home but this does not seem to work. I have also tried screenshotting Stories but this doesn't seem to work. I only screenshot ugly pictures of friends because they have a ton of me; I was unable to screenshot my friends' ugly snapchats for the longest time and they knew this and took advantage of the situation for almost 8 months. I stumbled upon this thread and now I can screenshot Snapchats, but not stories.
Again, only Snapchats are screenshot-able by using Volume Down + Home. I use the HTC One SV (exclusive for Cricket I think, now discontinued). Stories are not screenshot-able as far can I can tell. I can be wrong. Hopefully I am. Hope this helped.