That is certainly not nowadays... Even though yes, this may be doable in some places still (if you keep yourself to drinks and maybe some food for sharing)
For example: Buses that run most of the night (roundtrip) - about US$2.75, Beers (four Skols from supermarket) - about US$3. That's US$5.75. Meet your friends near the beach, in Lapa, at someone's home or at some predetermined free event (of which Rio has many). Even if the beer is bought while out, the night's bill upon returning home would be no more than US$10. Plus when I lived where I didn't have to take the bus in order to meet people on most occasions, it was even less. In places where there were nicer bars, there'd usually be many people hanging out on the sidewalk in front of the bars and inevitably, there'd be street vendors selling food and drinks.