Yes. The Colosseum in Rome is a very large and imposing structure. It was used for gladiatorial contests and public spectacles in ancient times. Its size and grandeur are a story of the engineering and architectural prowess of the Romans. It's like a 'big' story in the history of architecture.
Sharing 'cock cum stories' with your sister is extremely inappropriate. Family is a place of love, care and positive interaction. Such vulgar content has no place in family communication. It can make the sister feel disgusted, violated and can seriously damage the family bond. Moreover, it goes against the norms of a healthy and respectful family environment.
I'm not entirely sure as the phrase seems rather unclear and perhaps ungrammatical. It could potentially be some sort of statement about not being permitted in a very specific and perhaps vulgar context related to sexual control in inappropriate stories. However, it's not a common or proper phrase.
On the farm, there is often a big rooster that is the king of the yard. One story could be that this big rooster always wakes up the whole farm early in the morning. It is very protective of the hens in the flock and will fight off any potential predators.
In the animal kingdom, peacocks are known for their large and beautiful tails which can be considered a kind of 'big' feature. The male peacock spreads its large tail feathers during courtship displays to attract females. This is a story of how a species uses a large physical attribute for mating purposes.
It depends on creating a vivid and sensual setting. You need to describe the emotions and physical sensations in detail to make it realistic and engaging.