[Doll-Elf]

Betty Boop was made for adults and you cannot prove me otherwise. This was an adult cartoon and I love it.

The fact that she shrank out of her clothes is very interesting, considering it's not part of the original story, which means the animator, after having the others shrink normally said: "Nah, her clothes don't shrink with her so she's naked." (Neither is shrink-ola but it's a nice adaptation)

There are a lot of things hinting that there is more to this animation than was released. For example, with how she crawls through the tunnel, her hair, while long, flips up and down as she crawls. Sure, it's to show that her hair is so long, but it's also at the right angle and length for a tail.

My assumption is that the animator also made a furry version of this but never released it because it wasn't part of the story.

That isn't even all that uncommon as many stories have unreleased bits and "deleted scenes" as they could be called. What I think, is that the 'furry' version did exist but was slipped into a personal collection never meant for public viewing. This, along with the lewd nature of Betty Boop is enough to suggest that the shrinking scene likely had an even more naughty version.

However, we will never see it.