Broom sweeping arm
The arm that is used for repetitive action.
Person 1: Dude, my broom sweeping arm is aching
Person 2: What happened?
Person 1: I played squash for 2 hours
Person 2: ...wouldn't that make it your squash arm?
Person 2: What happened?
Person 1: I played squash for 2 hours
Person 2: ...wouldn't that make it your squash arm?