> How do I tell our HR that I don't want to “perform” in our Christmas
> party?

Dear HR,


I will not dance in our Christmas party because I feel myself unconfortable. Thank you for unserstanding.


Best regards,

donotexecuteorder66


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If you don't want to do something, you don't have to do something. Nobody will blame you because of this. Just tell(write) your boss and HR(if needed) as soon as possible. Make it clear that you don't want to and you won't do. Of course be polite. If I right understood, you will attend party and.. it is enough already.

**PS** Thanks to @MawgsaysreinstateMonica for email template edit suggestion