There’s a certain “cheering crowd” sound that seems to get played a lot. I’ve always been curious about when and where it was recorded. Not really sure how to describe it other than that its the “overplayed cheering crowd” sound, but I hope someone understands which one I’m talking about.
I thought the exact same thing when I first heard a real kookaburra. “Hey! I’m in a Tarzan movie!” (embedded audio file)
Nature show? Real life. Advantage of living in the Pacific Northwest. 
Anecdote: I was staying with some friends at a cabin on an island in south Puget Sound (for locals, this was on Vashon), including a visitor from out of town, New York City no less. I heard the distinctive call of a bald eagle outside, that fast high-pitched piping “ik-ik-ik” sound. I figured it’d be neat for a New Yorker to get a chance to see or hear one of these birds first hand, so I pointed it out. “Listen,” I said, “that’s the sound of a bald eagle.” We were silent for a minute, and the call came again. “No way,” she said, in that superior New York tone, “that’s not what a bald eagle sounds like.” I shook my head, but she argued, claiming she knew all about our national symbol. So we had to go outside and look around, and eventually we saw a pair of them sitting on a tall piling a few yards off shore. As we watched, one opened its beak and made the call: “ik-ik-ik…”
It’s not very often that a superior Manhattanite gets cut down by a left-coast local, but it was definitely a good moment.
Here’s an ABC story on The Wilhelm Scream.
Roger Ebert covered this recently- one of his readers dubbed it the “Flipper Giggle.” It’s not a real dolphin, but a human (possibly Mel Blanc, the Frank Welker of his day) imitating one.
Correction, in deference to chronological and sentimental precedence: Frank Welker was the Mel Blanc of HIS day…