"Get square" is a colloquial term that means to exact revenge or to settle a score with someone. There are several synonyms that can be used in place of this phrase, including "get even," "pay back," "retaliate," "balance the scales," and "settle the score." Other similar expressions include "get your own back," "give as good as you get," and "get vengeance." Using these synonyms can add variety to your language and help to convey the same message in different ways. However, it is important to remember that revenge is not always the best solution to a problem, and it is better to try to resolve conflicts through communication and negotiation whenever possible.