Bob Newhart tells a 9/11 joke.

You can joke about 9/11, can't you? You just have to find the right way to do it:

Reading recently about the Zacarias Moussaoui trial, his "button-down mind" found an angle on the 9/11 pilots, and he has been toying with it as a possible stand-up bit.

"They didn't want to learn to take off and land," he said. "They just wanted to fly. Some have criticized the F.B.I. because that should have been a red flag. But I saw it as a case of —" he studied his coffee table it as if it were a weekly planner — " 'O.K., well, I don't have to come in Monday; I can come in late Tuesday; Wednesday and Thursday, O.K., that's flying; and then I don't have to come in Friday.'"