Whimsy (noun)

1. Playful or fanciful behavior or humor.
2. An unusual or fanciful idea.

Origin:

The word "whimsy" comes from the middle english word "whimsie" which in turn comes from the old english word "whimsey" which means "a whim or fancy". the word has been in use since the 16th century.

Examples:

1. The children loved the clown's silly antics and whimsical jokes.
2. The designer's whimsical touch was evident in the unique and colorful clothing.
3. She had a whimsical idea to paint her front door bright pink.
4. His whimsical approach to life made him a joy to be around.
5. The whimsical sculpture in the park was a favorite among the visitors.