I tried taking a screenshot of my friend’s Snapchat story yesterday and didn’t get a notification, but I’m not sure if that’s always the case. Does it depend on their privacy settings or something?
Haha, trying to sneak a screenshot, huh? 
Don’t worry, Snapchat usually tattles if you screenshot a story—no secret agent moves here! My kid tried it once and got caught faster than I catch him sneaking cookies. 