The expression to have a ball means to enjoy yourself immensely, to have fun and to have a good time. A 'ball' is an archaic word for 'party'. This expression is used more in informal contacts or in social situations.

1. I really didn't think I would enjoy the concert but I'm so glad that I went. The atmosphere was fantastic and I had a ball.
2. Chris moved to Australia last year. Last time I spoke to him he said that he's having a ball over there and has no intention of coming home any time soon.

1. I had a ball at the conference I made a lot of great contacts and had a lot of fun at the events.
2. Having a stall at the convention was a great idea. We sold a lot of stock, introduced yourself to some new customers and had a ball at the after-parties.