When someone says they plead ignorance, they're admitting they didn't know any better or weren't aware of certain facts. There are a few other ways to express this sentiment, including claiming naïvete, professing ignorance, or feigning innocence. Using any of these phrases can come across as an attempt to avoid blame or responsibility, so it's important to be honest and accountable in any situation. Admitting your missteps and committing to learning from them is a more productive approach that can lead to personal growth and development.