"Uncle" is a term that denotes a familial relationship, whereas the phrase "said uncle" refers to a specific action taken by one individual to another. Although there are no direct antonyms for "said uncle," one could use a few phrases to imply the exact opposite meaning. For instance, one could say, "refused to acknowledge," "denied," "contradicted," or "disagreed with," instead of "said uncle." These phrases have a completely opposite meaning to "said uncle" and convey a sense of opposition, defiance, or refusal. By using antonyms for "said uncle," one can express a more nuanced meaning in their communication.