I'm not entirely sure what specific 'group of black cock stories' you mean. It could refer to stories about black roosters perhaps. If it's about black roosters, there could be stories of their unique behavior in a farmyard, like how they are more territorial compared to other roosters.
One possible story could be about a group of black cocks that were known for their early morning crowing. Their crowing was so distinct that it became a part of the daily routine for the people in the village. The villagers would wake up to their crowing and start their day.
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.
Yes, in some farming communities, there are stories about how black roosters are great at protecting the hen house from predators. Their loud crowing and brave nature are often part of these tales.