The phrase "be on pins and needles" is used to describe a state of extreme nervousness or anxiety. Antonyms for this phrase could include "be at ease," meaning to feel relaxed and calm, or "be nonchalant," meaning to display a casual and unconcerned attitude. Alternatively, one could use the phrase "be composed," implying a sense of self-confidence and control in a stressful situation. Other antonyms could include "be surefooted," implying a sense of stability and balance, or "be unflappable," indicating the ability to remain calm and collected in the face of adversity. These antonyms present a stark contrast to the tense and uneasy state described by the original phrase.