The phrase "letted it hang out" is typically used to describe someone who is being extremely casual or uninhibited in their behavior or appearance. Some antonyms for this phrase might include words like "concealed," "discreet," or "reserved." These terms imply that someone is being careful or cautious about how they present themselves to others, perhaps because they are in a professional setting, trying to make a good impression, or simply don't want to draw too much attention to themselves. Other antonyms for "letted it hang out" might include words like "controlled," "restrained," or "composed," which suggest that someone is purposely holding back their emotions or actions in order to maintain a certain level of decorum or self-control.