People call me a little mouse?

Your question is too general, so there are many answers.

For example, you look like a mouse .. I have a classmate who looks like a mouse, so we call him a mouse.

It could be a nickname. Boys and girls are sometimes called little mice, because there is a classic saying about little mice: If there is an afterlife, I hope we can be a pair of little mice, who love each other foolishly, rely on each other foolishly and snuggle clumsily. Even if the mountain is closed by heavy snow, we can hide in the cave and whisper. ..

Or do you like snacks very much? Sometimes we call this kind of snack-loving mouse a mouse. ..