Stock mad scientist pose in Japanese works of fiction. Both palms open and turned skyward, with arms spread open and raised slightly in a confident, 'welcoming' gesture. Arms may sometimes be raised higher above the head. Legs usually remain standing, spread apart slightly (though some may have them close together as if standing at attention).
Often accompanied with the stock exclamation of "SUBARASHII", hence the name. This is usually translated into English as "magnificent" (c.f. Bondrewd), "majestic" (c.f. Micolash), "marvelous" (also Bondrewd), "wonderful", "magnifique", etc.
Mad scientists in Western works may also sometimes strike a similar pose, but this is far less common, as they tend to prefer other more intimidating poses.
The Western equivalent, do not tag
The standard Western cliched equivalent generally involves one arm raised and clenched in a claw-like pose, with the other raised higher and 'pointed' towards the general direction of the viewer or another character. This second arm can be either 'open' or clenched closed, and is usually also holding another object: generally a test tube, flask, ray gun, wrench, or some other 'sciencey' implement.
