an unintelligent tea party or republican obstructionist; a word that sarah palin finds acceptable coming from a right-wing pundit but unacceptable coming from a spitfire dem.
Senator Shelby is teatarded for obstructing justice and blackmailing the country in order to get perks for his own state.
To the end that "tipping" refers to enjoying the occasional road soda whilst cruising with a friend down your local thoroughfare, a tiptarded individual would be one that did not learn to drink while riding in a car at the appropriate age, and therefore is not ever capable of mastering such as skill.
"Dude, that was totally 5-oh that we just passed. Why the hell would you take a drink of that Old E forty just then?? You are so tiptarded..."