hit it off, to

To form an immediate, positive connection with someone. I just knew you and Haley would hit it off—you two have so much in common. I'm so glad that you hit it off with my father. He isn't always the easiest person to get to know.

Fig. to quickly become good friends with someone. Look how John hit it off with Mary. Yes, they really hit it off.

Get along well together, as in I was so glad that our parents hit it off. In the 17th century this phrase was put simply as hit it, the adverb off being added only in the mid-1800s.

COMMON If two people hit it off when they first meet, they like each other and get on well together. Bill and Andrea seemed to hit it off last night. I had to leave — I didn't really hit it off with the new manager.

To get along well together.

To get along well (with someone). To hit has long meant, in a secondary sense, to succeed, probably from a sport or game. Shakespeare used it in this way in numerous plays; for example, “Have all his ventures fail’d? What, not one hit?” appears in The Merchant of Venice (3.2). To “hit it off ” seems to be an elaboration of the same meaning, and dates back to the eighteenth century. “How do you and the great Mrs. Montague hit it off,” wrote diarist Madame d’Arblay in 1780.