The overwhelming sadness that you get after the play/musical you were in closes. It is very hard to treat, as it is unlikely you will ever do that play/musical again.
Jim: Hey, what have you been doing since the show ended?
Joe: Not much, I've been dealing with a pretty bad case of theatrical depression. I haven't left the house in two weeks.
An arm movement commonly used by actors and singers.
Extend your arm forward with a bend of about 90 degrees at the elbow, so that the hand is level with and to the side of the face.
Now, bend the fingers into a claw-like formation, as if grasping something invisible.
Hold the arm in this position, thrusting the forearm forward to emphasise various words as often as necessary.