The phrase "pulling one's leg" refers to joking or teasing someone in a playful manner. Antonyms for this phrase would be terms that describe being serious, sincere or truthful. Words such as being honest, straightforward, candid, or direct would be appropriate antonyms for pulling one's leg. Other antonyms could include insinuating, misleading, deceiving, or manipulating. These antonyms describe actions that are opposite to the humor and friendliness that comes with pulling one's leg. It's important to understand the context of interactions with others to determine when it's appropriate to use joking or when it's necessary to be sincere and direct.