When it comes to finding synonyms for 'get someone back', there are several options available. The phrase 'revenge' is a common synonym implying that you are seeking vindication for a perceived wrongdoing. Alternatively, 'payback' implies that you are hoping to settle a debt between you and the other person. 'Retribution' suggests that you are seeking to impose a penalty for their actions. 'Retaliation' often implies that you are responding to an attack or wrongdoing that the other person has done to you. Finally, 'vengeance' is a more extreme synonym that implies a desire to do harm or injury to the other person. Ultimately, the best synonym will depend on the context and situation in which the phrase is being used.