I just figured out that it's the movie Spin. I definitely recommend it as a fun and complex movie about the club culture.
I have some clear details to describe, but I can't remember the name:
The main character is a DJ. He spends much of the movie trying to get together romantically with a hot female friend, but winds up with a nicer girl.
The DJ tries to ditch the girl the next morning by mentioning an imaginary dog he needs to walk, but another friend has actually brought a stray dog to his house.
In the middle of the story, this DJ winds up in a veterinary hospital, from which he flees naked.
Another sub-plot is that another man hooks up with a gangster's wife, and much trouble is expected. But in the end, the gangster is happy to have a photo of the tryst to use to divorce his wife. This confrontation happens at breakfast the next morning.
It ends with the young club manager telling them the next day that it is all about to start over again.