Losing an elephant does sound, well, uh a little far-fetched. But if I could be of any help, feel free.
13 seconds sound clip from The Yogi Bear Show - Hide and Go Peek (1959) - S01E22 TV Series.
You can hear this line at 00:04:08 in the Blu-ray version of the movie.
Quote context
[...]
- Nah, we ain't looking for no bears. Are we, Joe? Nah! We're looking for an elephant
- May I inquire what kind, sir? Striped, checkered, polka-dot?
- How about that? A bear comic.
- Ah, skip it, smarty pants. Let's go, Joe.
- Yeah. How long can an elephant hide?
- That's okay. Forget it, chum!
- Lookie, Charlie. Elephant's footprints, leading right into that smart-aleck bear's cave
[...]