けっさく傑作kessaku
1.

A work that stands out for its exceptional quality and excellence in creative achievement, often recognized as a significant contribution in its field.

2.

An instance or creation that, while intended to be serious, is perceived as peculiar or absurdly amusing by others, often carrying a light-hearted irony.

3.

A remarkable or extraordinary occurrence that is both funny and entertaining, despite having occurred without any deliberate planning or design.

Example:

その偉大な画家の傑作が壁にさかさまにかかっているを見て、彼は驚いた。