The phrase "sticking one's neck out" means to take a bold or risky action, often with potential consequences. Antonyms for this phrase could include being cautious, playing it safe, or avoiding any sort of risk. Instead of taking a proactive approach, one might choose to simply go with the flow or follow the status quo. Other antonyms could be staying in one's comfort zone, remaining silent or passive, or not making any waves. While taking risks can often lead to great rewards, sometimes it is wise to weigh the potential costs and benefits before sticking one's neck out.