Nearly erupted in an intense display of emotion, usually anger or laughter. I almost lost it on the waitress after she messed up my order for the third time.Paul almost lost it at the airport when he found out that his luggage was missing.Wow, when he slipped on that banana peel, I almost lost it.
Fig. to nearly lose one's temper, composure, or control, as out of anger. I was so mad, I almost lost it. When he saw the dent in his fender, he almost lost it.