A messaging application that causes the sent message or video to disappear in the recipient's device after a short duration.  Snapchat introduced the concept, and Instagram later added that feature.  Facebook's Slingshot was a variation in 2014 but was later taken off the market.  Slingshot recipients saw only a low-quality thumbnail until they reciprocated by sending their own image to the sender.  See 
Snapchat and 
Instagram.