adj. the inability to use t9 (predictive text). t9 was designed to make typing text messages easier; however, the user must be smarter than the phone for feature to work properly. t-tardedness is enhanced with alcohol consumption.
"dude - do you ever read your nonsense texts before pressing the send button? you're totally t-tarded!"
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.