The nightlife in Brazil is not like other countries. It's a whole lot more fast and loose. In most countries there's a time that bars stop serving alcohol. In Brazil you can buy drinks curbside 24 / 7 out of a cool box !
As a foreigner in Brazil you can actually experience more things than the locals because you wont be subject to the class prejudice that exists in Brazil and you won't have financial limitations.
That is to say the people who go to street samba and favela Baile Funk parties can't afford the up market bars and clubs, and the people in the up market bars and clubs wouldn't be seen dead at a street party (though the rules become more flexible at carnival).
A night out in Brazil is like a long ride on a roller coaster. Whilst some countries it's illegal to serve alcohol after 2 AM, in Brazil the parties will of only been rocking for a couple of hours by that time. If you're home before sunrise the night can't be considered a success !
Brazilians don't hit the bars until at least 23:00. Unless you get into Brazilian soap operas there's not that much to do in the early evening apart from go out for dinner.
The style of drinking / socialising establishment in Brazil generally fall into 5 categories:
Botecos - Small street corner type bars selling beers and food to all and sundry. These are good for practising Portuguese in and as a starting point or for warm up beers.
Smart bars and clubs - For people with money to spend. They are much like you'll find in your home town and you'll have to show I.D. to get in.
Bar Restaurants - There are more of these than bars. They have waiters serving the tables with a full course menu or just drinks if you want them.
Street parties - There are whole blocks in most Brazilian cities turned over to night life and hundreds of people will congregate around the bars and restaurants, this is where you'll often see people selling drinks curbside out of cool boxes ! The most famous in all of Brazil is Rio's Lapa. The main night is a Friday so don't miss it when you visit.
Baile Funk parties - These are the kind of parties you can only get to if you meet people as they are held outdoors and not in the tourist parts of town. Quite often they are held in the favelas with local i.e. gang security. Definitely the ultimate aim for the backpacking traveler.
Guapo Loco is a bar restaurant club converted from a house.
In the smart bars and clubs the bar service is different to how you'd recognise it at home. When you enter you'll be given a card, with your name on it, which shows the entire selection of drinks on the menu with tick boxes next to each drink. When you get to the bar and order the barman will give you your drink and mark your card with what you bought. Before you leave you have to pay the bill in full at the cash desk. They stamp the detachable receipt which you have to show to leave the bar. If you loose your card you will be given a hefty fine.
Brazilians are generally considered to be steady drinkers and don't get drunk like say the English or the Irish do ! Getting absolutely hammered and acting and idiot won't make you any friends in Brazil.
Our top tip for nights out in Brazil is to print out a copy of the phrases in our language section, buy some of the locals a few beers to help with the translation and party on !