If you are in Budapest, there is a company which does a bunch of free walking tours. General, Communist and Jewish. The guides are Budapest natives, really cool faces. They usually party a lot and take travelers with them to the hottest nightlife actions too.
So daytime you learn about the history, society, architecture and people of Budapest, at night you learn about the most authentic Hungarian pubs and the way locals are partying. You know the more thrilling venues are often hidden from plain view...