Is it okay to massage my boss's feet?

I normally don't do that and i would do that only do it for my significant other but my boss the owner of the cloth shop i work at asked me to do it, she just put her feet up and asked me to massage them and ugh they were cold and sweaty and now she occasionally asks for one from time to time, now if I said no she will probably add me to her " blacklist" and she already fired people, should I just do it or she will probably asks for more stuff in the future and it would be unacceptable? Pls help with your thoughts
Is it okay to massage my boss's feet?
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