(baseball) A pitch thrown with added pressure by the index finger and a twisting wrist motion resulting in a motion to the right when thrown by a right-handed pitcher.
The screwball is not thrown much because it tends to damage pitcher's arms.
I will not listen to this screwball any longer.
Also a big hand for Silver Linings Playbook, an exuberant modern screwball comedy we had, in an unseemly fit of cynicism, deemed "too entertaining" for Academy voters.