derives from the term {retard] it's not PC but merely refers to somebody socially undeveloped- sometimes it's needed! you people know who you are!! Oh and it also means to be late tardy but I prefer the first expression.
"erm no sorry I don't do tards"
"do you have to be so tarded??"
Someone who does something stupid for the first time. (Somebody who does something stupid a second time is a retard).
Why did you pick the Cubs to win the World Series last year, you tard? Why did you pick the Cubs to win the World Series this year, you retard? -See the difference?