Somebody forwarded this clip of Paul McCartney performing "A Day in the Life"/"Give Peace a Chance" in a tribute to John Lennon at the recent Live at Liverpool 2008 festival, which was attended by both Yoko Ono and Olivia Harrison. He pulls it off pretty well, too, but there's an awkward moment when Paul flubs a line (which really isn't surprising seeing that he probably hasn't performed the song in more than 40 years).
What is ironic, however, is that McCartney's mistake comes in the part of the song *he* wrote. What's more, this bit has apparently always given Paul trouble. In a well-known outtake from Sgt. Pepper, he can be heard tripping up in the same place and adding "Oh, shit!"
Words fail me.