I'm not sure exactly what you mean by a 'big cock shrink story' in a non - vulgar sense. It could potentially be a story about a large bird (cock as in rooster) that seems to become smaller in some way, like if it gets wet and its feathers flatten, making it look smaller.
In a magical land, there was a giant rooster. It was known far and wide for its huge size. One day, a wizard cast a spell on the land that affected the rooster. The spell made the rooster's feathers become very tight against its body. It also made its body seem to shrink. The rooster was confused and the other creatures in the land were amazed at how the once - big cock had become so much smaller. This change led to a series of adventures as the rooster tried to find a way to break the spell.
Another topic is about the legal rights and challenges they face. For example, the fight for marriage equality in different regions and the ongoing struggle to end discrimination in employment, housing, etc. This shows their journey towards full equality in a complex social environment.
One of the best slow shrink stories could be about a small town that gradually shrinks in population over the years due to economic decline. People move away in search of better opportunities, businesses close down one by one, and the town slowly becomes a shadow of its former self.
One 'friend shrink story' could be about two friends who had a big argument over a misunderstanding. For example, one friend thought the other had spread a secret, but in fact it was a miscommunication. They stopped talking for a while and their friendship shrank. But then they cleared things up and rebuilt their bond.
Yes, there are some relatively popular ones. However, they are mostly spread across various fanfiction platforms. Some might gain popularity because they have unique takes on the shrinking concept, like how the Pokémon's abilities are affected when they are shrunken.