The world's smallest violin is basically a regular violin except it is far much smaller. Depsite its size, it still sounds like a regular-sized violin. Hence its name, it is considered to be the world's smallest violin. The song played on the violin is "Woe is Me!"
Role in episode
The world's smallest violin is played a total of three times in the episode "Squilliam Returns." Mr. Krabs first plays it after hearing Squidward's story on how he must beat Squilliam.
The violin is played a second time after Mr. Krabs hears Squilliam telling Squidward that he was a cashier too (which was false).
The violin is played one last time right at the end of the episode when Mr. Krabs appears by a saddened Squidward. The latter replies by saying "Would you get out of here?!"
Mr. Krabs playing the world's smallest violin has some hits on YouTube, such as remixes and longer versions.
Judging by the scale measurement to Mr. Krabs, the violin is approximately a third of a centimeter, making it truly the world's smallest violin. However, if it were real it would play at a much higher frequency.