Flapdoodles is a rather uncommon word that refers to nonsense or foolish talk. The antonyms for this word could be sensible talk, wise words, or logical reasoning. Some other antonyms for flapdoodles might include sobriety, seriousness, and practicality. If someone is talking flapdoodles, they are not being rational or logical, so antonyms would be words that suggest thoughtful or intelligent speech. Other antonyms might include realistic, meaningful, and pragmatic. Ultimately, the opposite of flapdoodles is a factual and informative discussion, one that is based on evidence and reasoning rather than mindless chatter.