1. Because it's fun
2. In cities, different kinds of people exist and mostly (not always) get along. Some women like this sort of thing, others don't. Sometimes, the people who do this might even be more interested in attracting men. The thing that's attractive about cities is you don't have to be one way to avoid getting attacked or ostracized. If you can try to internalize that, a lot of things that confuse you now will make a lot more sense