From a Washington Post account of Addington’s testimony:
When John Conyers (D-Mich.) inquired about Addington’s pet legal concept, a “unitary executive theory” that confers extreme powers on the president, Addington dished out disdain.
“I frankly don’t know what you mean by unitary theory,” Addington replied.
“Have you ever heard of that theory before?”
“I see it in the newspapers all the time,” Addington replied.
“Do you support it?”
“I don’t know what it is.”
The usually mild Conyers was angry. “You’re telling me you don’t know what the unitary theory means?”
“I don’t know what you mean by it,” Addington answered.
“Do you know what you mean by it?”
“I know exactly what I mean by it.”
More from Marty Lederman at Balkinization on John Yoo’s testimony.