I was about to launch into song once and somebody said "Sing that one you did a few weeks ago".

"Which one was that?"

"Can't remember."

"What was the title?"

"Can't remember."

"Well, what was it about?"

"Can't remember."

"Can you remember any of the words?"

"No."

(In desperation)"Can you remember the tune?"

"No. But it was a good song though."