(humorous) A notional violin that plays tragic music for the afflicted; used in dismissive responses to oversensitive complaining.
2007, Joseph P. Natoli, This is a picture and not the world: movies and a post-9/11 America (page 109)
The world's smallest violin playing hearts and flowers for every sweetheart of the Midwest who didn't make it in Hollywood.
2008, Patsy Clairmont, I Second That Emotion: Untangling Our Zany Feelings
He stretches out his arm and then rubs his thumb and forefinger together as if he is playing the world's smallest violin for the world's largest whiner. How rude is that?
2010, Geo Gosling, TBI Purgatory: Comes After Being in TBI **** (page 102)
Even someone upset about something as serious and awful as cancer wasn't safe from my world's smallest violin. Well, you have cancer. That sucks but cancer has been beaten.