He shrugged his shoulders.
Is there anything else that can be shrugged, besides shoulders? To me it sounds like duplication when used in this way. I'm aware of constructs like "He shrugged it off." but that's not what I'm interested in, and it also implies the use of shoulders, doesn't it?
So why the need to specify the shoulders as an object?
[edit: I also find "he shrugged his eyebrows" but that's rather rare.]