David Letterman was the target of a death threat in posts on an extremist networking site frequented by al-Qaeda, according to SITE Intelligence Group.

The private company, which trolls the web for possible terrorist activity, reported the call to "cut the tongue of this lowly Jew and shut it forever."

This frightening threat is believed to have arisen after Letterman, who is not Jewish, cracked a joke on Late Show perceived as offensive to Islam.

"He showed his evil nature and deep hatred for Islam and Muslims, and said that Ilyas Kashmiri was killed and he joined bin Laden," Umar al-Basrawi, which is probably not this lowlife's real name, wrote online.

"We ask Allah to paralyze his tongue and grant the sincere monotheists his neck."

Analysts perceived the diatribe against Letterman as "a more explicit threat" than a similar one aimed at South Park creators Trey Parker and Matt Stone.

A rep for Letterman's Worldwide Pants production company respectfully declined to comment, but SITE is advising the funnyman to be on his guard.