An onomatopoeic adverb meaning to complain, nitpick, or make excuses; often used in phrases like “Don't complain” (つべこべ言うな).
つべこべ言わずにまずやってみろ。
Stop complaining and try doing it first.
彼はいつもつべこべ言って行動に移さない。
He always nitpicks and never takes action.
説教してもつべこべ反論するだけだった。
Even when I scolded him, he just argued back and nitpicked.