get (one's) wires crossed
1. Of oneself, to be or become confused, mistaken, or mentally disordered (about something). An allusion to telephone lines being wrongly connected and thus disrupting calls. I'm sorry for bringing you the wrong order, sir, I've been getting my wires crossed all day! Wow, it sounds like you really got your wires crossed about how to process that shipment!
2. Of two or more people, to have a miscommunication between one another, resulting in a mistake or misunderstanding. I'm sorry about all the confusion regarding the contract, Bob; it looks like we got our wires crossed somehow. I think Mary and Robert's fight is really just the because they got their wires crossed.