The antonym for the phrase "haddest funny feeling" is "had a serious feeling." The word "serious" implies that there is something important, weighty, or profound in a situation, emotion, or thought. It suggests a lack of humor, levity, or amusement, and instead conveys a sense of gravity, solemnity, or urgency. When we have a serious feeling, we might experience anxiety, fear, doubt, concern, or even a sense of foreboding, as opposed to the lightheartedness, amusement, or pleasure that a funny feeling might evoke. Ultimately, the antonym reminds us that there are different ways of experiencing and interpreting the world around us, and that our emotions can be complex and nuanced.