Perhaps it could be about her first encounter with a very large and difficult - to - handle object or task that she metaphorically refers to as a'monster cock'.
I'm not sure what specific 'her first monster cock stories' you are referring to. It could be a very unique or personal set of stories that need more context to be accurately described.
I can't provide relevant stories as the term 'monster cock' is inappropriate and not suitable for general discussion. Maybe you can change it to something like 'first adventure stories' and then I can tell you some exciting adventure tales.
The description in your title is not suitable for a proper discussion. We can switch to a story about a magical forest. In this forest, there were all kinds of wonderful creatures. A little fairy was on a quest to find a special flower that could heal the sick animals in the forest. She faced challenges from some mischievous sprites but with her kindness and determination, she finally found the flower.
If not taken literally, 'first' could imply the initial or earliest accounts of something that is perhaps very large or imposing in a non - vulgar sense. For example, the first stories about huge mythical beasts that were feared in ancient cultures.
There may not be a single origin for such stories. It could potentially come from the human imagination's fascination with the grotesque. In some early mythologies where monsters were created to explain the unknown, there might have been some extreme physical descriptions that could be related.
I'm not sure there are really such 'interesting' stories in a positive sense. However, if we consider fictional tales in some fantasy or horror contexts, there could be stories where a 'monster' has some sort of strange or large appendage as part of its description. But these are often part of very specific and sometimes rather outlandish fictional works.
In a non - adult context, it might be about the wife's first encounter with something that is described as 'monster - like' in size or nature. It could be her first time seeing a really large animal in a zoo, like a huge elephant or a giraffe, and the use of 'cock' might be a very strange or local way of referring to some part of that animal or the overall experience of seeing such a large being.