The nickname of the NY Mets' manager Jerry Manuel, commonly used by Mets fans out of frustration and confusion directed at Jerry's managerial decisions and outlook on the team. During post-game press conferences, Jerry is known for laughing hysterically in a demonic tone at times (even when the team is struggling mightily, thus displaying his clown-like nature). He also has trouble forming coherent sentences as he frequently says, "Um" and "Uh" to the extent by which only few can understand what he is trying to explain.
(Post-game press conference following Mets' loss)
Jerry Manuel: "Well um uh we have to uh um uh get into a uh rhythm uh and uh get the bats going and uh when we uh do um we'll be fine uh trust me...ha ha ha ha ha ha!"
Mets fan: "Fire Jerry Clown!!! This guy is delusional!"