Another moral could be related to the cycle of nature. The rooster is a part of nature and its interaction with the girl can symbolize how humans are also part of nature's web. We should respect all living beings and their natural behaviors. If the girl was initially scared but then learned to co - exist with the rooster's sometimes - erratic behavior, it shows that we can adapt and find harmony with nature.
I'm not aware of any specific "huge cock in tiny mouth stories" in mainstream literature. Most literature focuses on more positive, moral, and diverse themes.
Educate oneself about appropriate communication. Learn about the values of respect and decency. Also, if you encounter someone bringing up such inappropriate topics, firmly but politely let them know that it is not acceptable behavior.
It might be a very specific story where a girl has an interaction with a rooster and the action of the rooster getting near her mouth is a central part of the plot. Maybe it's a story from a rural area where animals and humans interact closely on a daily basis.
One attached paranormal true story I heard was about a haunted house. A family moved in and soon noticed strange things. Doors would open and close by themselves at night. They often heard faint whispers when no one else was around. One night, they saw a shadowy figure moving across the hallway. Eventually, they couldn't take it anymore and moved out.