The phrase "be pins and needles" is often used to describe a physical sensation of nervousness or excitement. However, there are several antonyms for this expression that convey a sense of calmness and relaxation. For example, "be at ease" is a common phrase that suggests a mental and physical state of peace and tranquility. "Be calm" and "be laid-back" are also antonyms of "be pins and needles" that suggest a sense of composure and serenity. Additionally, "be in the flow" implies a state of focus and immersion, while "be centered" suggests a state of balance and stability.