The phrase "phony up" is a colloquial term used to describe the act of falsifying information or evidence. Antonyms for this phrase include words and phrases that denote honesty, authenticity, and truthfulness. These words include genuine, real, legitimate, valid, honest, legitimate, and bona fide. When used in a sentence, antonyms for "phony up" can replace the phrase and indicate trustworthiness or a high degree of integrity. For example, instead of saying "they tried to phony up the data," one could say "they presented legitimate information that was fact-checked and verified." In this way, antonyms for "phony up" can help communicate a sense of honesty and credibility.