it's a bird

Today's xkcd cartoon, a features list for bird/plane/Superman, is one of the funniest I've seen lately. It also rings something in my head that I can't identify. I hear in my head a voice - and it's without visuals, so this isn't a movie/tv show, nor a book, but either radio or a record - saying:

"It's a bird! It's a plane! *yccch* It's a bird."

I hear it distinctly, but I'm drawing a blank on remembering where it's from.

Probably it'll hit me the next time I hear whatever it is.

This has happened to me twice before with lines that popped into my head. In each case I did not, at the time, own a copy of the source, so it was years before I happened to see/read that source again (one was a book, one a movie), and I suddenly remembered: ah, that's where that comes from.

One was:

"We are the chorus, and we agree. We agree, we agree, we agree."

which is from the parody of Galadriel's lament in Bored of the Rings, and the other is:

"Who are you who are so wise in the ways of science?"

which is spoken by Bedevere to King Arthur in Monty Python and the Holy Grail after a little experiment involving a witch and a duck.