Spotted this Street Booze the other day on Girard between 11th and 13th, it's Schlitz Original Malt Liquor with a straw. I recommend going to the Schlitz website for overly fancy descriptions of the various kinds of malt liquor they have.
As for the straw, the only explanations I can think of are that sometimes you may want to be able to drink and walk at the same time, and some people think it gets you drunk faster. And in an interesting factoid, Wikipedia tells us that the earliest known drinking straw was used by the Sumerians in about 3100 BC, and was actually used for beer.
Curious about more Street Booze? Check out the archive.