Xian is a big city with lots of things that you can do to get fun. Chinese people like Karaoke which offer different private rooms for the singers to sing all kind of the musics, it is very fun. The cost for the Karaoke is quite cheap, some of them even include the buffet meals. However, it is not a popular thing any more. There are a few Karaoke Clubs still operating in Xian.
There are some well-known pub streets in Xian, where you can find out different style bars and pubs. It is nice to taste the local beer and kill the night time.