小丑撕心裂肺
[xiăo chŏu sī xīn liè fèi]
The 'clown' is generally used to refer to oneself as being comedic, sometimes tragically so; 'Tearing one's heart and lungs' describes the state of being extremely pained or anguished - thus indicating deep pain hidden behind a mask of jest and comedy, possibly due to pretending all is well when faced with difficulties.