Glenn Beck responded to Keith Olbermann's special comment Thursday on his radio show.
Beck played audio of Olbermann, who had returned temporarily from vacation to comment on the Shirley Sherrod scandal and Fox News' role in driving the story..
Olbermann drew a comparison, which he admitted was a "stretch," between the slandered Sherrod and Alfred Dreyfus, the French military officer of Jewish descent who was falsely accused of treason in 1894 — only to be exonerated years later.
"Only Keith Olbermann would expect that you knew French history," Beck said, laughing.
Olbermann also ripped Fox News, calling the network a "perpetual fraud machine."
Beck repeatedly stopped Olbermann's 10-minute commentary to ridicule and personally attack Olbermann.
"I got my degree at an agriculture school, you simpleton!" Beck said, impersonating Olbermann. "Now plow that field!"
He then broke character to add, "What a dope."
Later, again imitating Olbermann, Beck said, "I have sat at this desk for seven years and my ratings tell me I won't be sitting here for very much longer. They've taken one of the worst guys on television and had him fill in for me and they're already starting to hire a staff and graphics for his show."
Before dissolving into laughter, Beck signed off with "Thank you for that history lesson, Keith. You are so far from a joke."WATCH: