Caused by overworking the Central nervous system of the brain. Eventually certain parts of the body start to shut down, usually starting with the left foot and working its way up the body. Although T.S.D. is very rare, there have been 37 recorded deaths.
Stephen Hawkings is the most well known person who suffers from T.S.D. (Too smart Disease) Another well know case was Franklin Roosevelt
when you're holding up your phone and making faces at it, as though you are taking a selfie, but you're really taking a picture of the person across from you or the wall or anything else that seems interesting but you don't want to be caught dead taking a picture of.
This action is often made more convincing by wiggling the eyebrows or opening the mouth, to pretend you're trying to get a Snapchat filter to work.
FRIEND A: "Did you just take a stealthie of me?"
FRIEND B (turning phone around): "no I was just using snapchat's new filter, see?"