In an episode in the first season(?), she says “I hope you weren’t too hard on the Beaver.” https://www.youtube.com/watch?v=F7AQkui_fcA. I was watching it on Netflix and snickered when she said that line.
I’m not sure if she said the exact words “Ward, you were too hard on the Beaver last night.”
I guess it could be just a very unfortunate bit of timing that a character’s nickname took on a risque meaning. Only a few years after it left the air.
It’s one heck of a coincidence.
Was Beaver ever a nickname for Theodore, common or otherwise, before or since? I don’t recall that I’ve ever heard it used that way. (ETA: Except on Leave It To Beaver.)
(It’s plausible that Beaver could be a nickname for any little kid with buck teeth. (Remember Bucky Beaver?) But that has nothing to do with being a diminutive for a name.)
See my post #11. It was a unique nickname based on Wally’s pronunciation of Theodore.
It is kind of odd, though, that this explanation wasn’t offered until the final episode.
My aunt’s nickname in our family was based on the way I mispronounced her name when I was two.
Leave It To Teddy just doesn’t have the same ring to it. 
I seem to recall there was an animal nicknaming fad in 1940’s and 50’s preppy colleges? Moose for example. I can’t recall any other examples just vague memories from old movies from that era. I’m not sure if that was a real life thing or not.
It couldn’t have been too risque in the mid '70s, as it was used as trucker CB slang for “woman”. Most/all CB slang had to be clean, because the FCC didn’t allow profanity or outright risque speech over the airwaves.
It was used pretty graphically in One Flew Over the Cuckoo’s Nest, 1975:
[QUOTE=McMurphy to teenage resident of the asylum]
What are you doin’ here? You oughta be out in a convertible bird-doggin’ chicks and bangin’ beaver.
[/QUOTE]
The Bouton book was my first acquaintance with the phrase.
In 1920, the Hudson’s Bay Company, granted a royal charter in 1670 to control the fur trade in British North America, began publishing The Beaver, a history magazine. In 2010, it changed its name to Canada’s History, in part because spam filters kept people from finding it online. Many older subscribers were outraged and people had an interesting time explaining the interweb, spam, and the beaver.
Definitely used and understood by many by 1965. In print by that date . Evidence exist that it was known and used by smaller numbers as early as the 1930s.
I would say, if the last definition dates back to 1927, it IS slang. If you don’t hang with those who talk trash, you won’t know the term. I know many today who do not know the slang meaning because…? Yes, damn it! Some of us still have class in this trashy world.
It was well known in 1965. I was watching “How the West Was Won” and there was a scene were some trapper met a wagon train. He was showing his pelts to them and a young woman said, “I’ve never seen a beaver before.” The place erupted in laughter.
So I can only assume no one reads Kurt Vonnegut anymore. Too bad.
Oops. Apologies to D18.
Apology accepted!
Sometimes a beaver is just a beaver…
Considering that beaver pelts were instrumental in opening up the wilds of Canada, the raison d’etre for the Hudsons Bay Company, the beaver is on the Canadian nickel, and is pretty much our national animal, there’s a limit to how risqué it can be except in context.
Beaver cheaters.
Beaver shot.
Beaver tracks.
Brings back memories.
Out here in the great Pacific Northwest the sobriquet “bearded clam” is also used.
Molson Canadian “Chasing Beaver” Commercial. It says it is from 1965.
The Double Entendres are not subtle.