I'm not sure specifically what 'ped cum mg secret story' refers to as it's not a common or well - known phrase. It could be something very specific within a particular context, like a local legend, a family - related secret story, or perhaps a made - up or misnamed thing.
It might be a very creative or misphrased attempt at something. 'Ped' could potentially refer to pedestrian in some odd context, 'cum' might be misused here as it has inappropriate meanings in some cases but could also potentially be part of a made - up word like 'cumulative' in a very strange way, and 'time stop story' could imply a story involving the stopping of time, but without more background, it's really hard to say for sure.
Well, it's a really strange set of words to base a story on, but here goes. There was a ped, let's say a young pedestrian named Tim. One day, he seemed to experience a 'cum' - like event, not in the inappropriate sense but like a culmination of things. Suddenly, time stopped. In this time - stopped world, Tim was able to see things he had never noticed before. The world around him was frozen, and he started to explore this new state of existence, wondering how he could get time to start again and return to normal life.
One possible interpretation could be that 'ped' is short for 'pedal' and'mg' might refer to a type of machinery or vehicle part, and the'secret story' could be about some hidden or interesting event related to pedals and that part in milligrams. But this is just a wild guess.
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.