I'm not sure specifically what that fanfic is about as I haven't read it. It could potentially be about a fictional relationship or adventure involving Matthew and Jay Bilzerian.
One moral could be to think before you speak. Just like in the story where the boy spread false rumors without thinking. If he had paused and considered the truthfulness of what he heard, a lot of trouble could have been avoided.
Definitely. There may be a story of a person who, through their 'big mouth', shares their journey of overcoming an illness. They talk about all the details, the good and the bad, which gives hope to others who are going through the same thing. Additionally, a social activist with a big mouth might be constantly advocating for environmental protection. Their loud voice and unwavering stance draw public attention to important issues and eventually lead to positive changes in environmental policies.
A 'big mouth romance novel' often has characters who are very vocal about their feelings. They don't hold back their love, anger, or jealousy. For example, in some novels, the hero might openly declare his love in a grand and dramatic way.