The phrase "pile in" means to enter or board a vehicle or place quickly and without hesitation. Its antonyms would include "delay," "procrastinate," "hesitate," "dawdle," "tarry," or "loiter." These words suggest taking one's time and not acting immediately. Other antonyms could be "exit," "leave," "evacuate," or "abandon," which indicate the opposite of entering or boarding. Using antonyms of "pile in" can be helpful in describing a situation where urgency or promptness is not required or where caution is advisable, such as when leaving an unsafe or unpleasant location.