When the level of someones "tardness" is so high that the word pants must be added on to the word tard. Like when someones says fancy pants, smarty pants, stupid pants, ugly pants...ect.
"Todd thought that if you light a fart on fire then the flame will burn your intestines. Todd is a tard pants"
"Hey man do you want to go punch some babies? Its a lot of fun!"
"Dude youre a tard pants.."