Is Your Writing Quirky?

Sometimes, when I read descriptions of what agents are looking for, they say things like "middle grade novels with quirky characters". And sometimes books are described as "quirky". What exactly does that mean? I looked up quirky using define with Google:

Quirky: Characterized by peculiar or unexpected traits

When I think of quirky, I think of something you wouldn't find just anywhere. Something that's a little bit different, and special because it's different. It's a book with things you wouldn't normally think of together (but a middle grader might).

Quirky fits well with writing middle grade, because 9 to 12-year-olds are at an interesting place in their lives. They sometimes play like younger kids, creating intense imaginary worlds, but a few minutes later, they might be texting friends like a teenager. They can act all sophisticated by choosing the perfect school outfit and then come home and work on capturing more crickets for their collection. For me, quirkiness is one of the reason why I enjoy reading (and writing) books for middle grade readers.

What do you think "quirky" means? How can you capture "quirky" in your writing?