The word has a lot of meanings depending on the context in which it is used. The word has a lot of negative connotations but it is also rarely used in a positive manner.

1. It can be used (but not limited to) to refer to someone who is dumb, uncivilised, dirty, rude, a failure, shady and more.
2. From a positive it can be used sarcastically to call someone naughty or funny.