A large fountain pen refers to a kind of pen, usually thicker than an ordinary pen, or an oily pen in a fountain pen. Because of the thick lines, you can write thick handwriting, which is common in drawing, doodling, signing and other occasions. In some artistic fields, large brushes are often used for graffiti, painting and other creations. Because of its thick lines, bright and direct colors, it is very expressive.

A big pen can also refer to people's attitudes or opinions about something or someone. For example, when others hold different opinions and criticize a person's behavior, they can use "holding a large sum" to express their negative comments. This usage usually has a certain teasing meaning, which is common in jokes between friends.

In some popular cultures, the big brush also has some derivative uses, such as expressing surprise and appreciation for someone or something with a big brush, or expressing a strong expression of some experience and emotion with a big brush. These usages usually have some exaggerated and playful tone, have a certain sense of humor, and also make people feel a little relaxed and fun in daily life.