The phrase "clean one's act" often refers to taking action to become more responsible and respectable in one's behavior, attitude, or habits. However, there are several antonyms, or opposite meanings, to this phrase.
One such antonym is "mess up," which means to ruin or spoil something or to behave irresponsibly. Another antonym is "neglect," which means to fail to give proper attention or care to something or someone important. "Slack off" is another antonym, indicating a lack of effort or dedication to a task or responsibility.
In contrast to "clean one's act," these antonyms suggest a disregard for responsibility and a lack of desire to improve oneself. It's important to recognize these antonyms and strive towards positive changes in one's life.