A combination of 'Liberal' and 'Retard.'
A libtard holds extreme liberal beliefs based on little more than what he or she wants to hear. Most information received will be internally filtered or even changed into something that better fits into their liberal worldview.
A libtard will often have the same attitudes and pigheadedness of an extreme conservative, and neither side seems to understand the irony.
Jimmy is a libtard. He believes everything documentaries like Farenheit 9/11 say, because it sounds like what he wants to believe.