A spontaneous, thoughless, predictable and stereotypical reaction to something, usually an opinion or a statement.
An entire culture of American neo-conservatives has seemed to build itself on a type of knee-jerk reaction to any kind of criticism of the Bush Administration or the loyal element of the Republican Party, even from fellow conservatives -- the kind of pseudo-patriotism discouraged by Theodore Roosevelt.
LN3: "between Iraq, the inability to catch Osama Bin Laden, the current economic meltdown, our foreign relations with what were previously friendly nations accross the globe I'd say that George Bush was a horrible leader and president."
AudiDefector: "that's nothing but knee jerk Bush hatred based on no facts, why do you hate freedom ?"