The word "most straightfaced" implies a serious and stern demeanor. Its antonyms are words that suggest lightness and humor. Some examples include the following: playful, witty, humorous, jovial, jocular, animated, lively, and cheerful. These antonyms convey a sense of whimsy and laughter, which directly contradicts the somber mood conveyed by "most straightfaced." By using these antonyms, we can describe a person or situation as being more relaxed and approachable, making it easier to connect with others. Whether we are describing a comedian, a friend, or a lighthearted event, these antonyms provide an effective way to express the opposite of "most straightfaced.