Just in case you know a "debt truther" show 'em this fine article by Michael D. Tanner.
It’s not quite on a par with 9/11 truthers or Obama birthers, but recently a number of liberal commentators have descended into the fever swamps of denialism by rejecting the most basic facts about our debt and deficit. Mind you, they are not arguing about the best policies to reduce the debt — taxe hikes vs. spending cuts — but actually denying that the problem exists at all.
And note that Larry Kotlikoff estimates the "U.S. fiscal gap" at $222 trillion. Of course that was six months ago.