Step 1: After receiving a snap “Tap to Load” the image but don't open it.
Step 2: Swipe to bring up control center and “Enable Airplane Mode”
Step 3: Open the snap and feel free to Screenshot or just view.
Step 4: While still in Snapchat. Hold the “Power Button” till the slide to power off button appears.
Step 5: Release the “Power Button” and then hold the “Home Button” till the app crashes.
Step 6: Turn off “ Airplane Mode” and noticed that the snap is still in your feed.