I took years of Espanol in high school, and absorbed all of about a dozen words. Later I got a job at a factory, where most of the workers spoke Spanish. I learned a lot more there than ever did at school. Not that I became fluent or anything, but can understand somewhat and make my way through a city. And I know l lot of the bad words too. I think the suggestion of watching Spanish TV is a good one. And some of those Spanish soaps are HOT.
Some of the common slang you will hear on the street is pretty damn funny.