In my case, it's "Old Timer's Disease." It was always hard to come up with plausible excuses when I was younger.

My all-time favorite "recovery" was a fellow who forgot one verse of a very long song. He substituted a single verse from a totally different song, with a different key and different tempo, after which he jumped back to the place where he had left off, continuing as if nothing had happened. I don't know, to this day, how he did it - or how he kept a straight face through the whole thing. People were laughing so hard, they forgot he'd screwed up!