Oh, probably not the one you are thinking of. The 42 is not just any bus. It goes to Chinatown, downtown, Dupont, Adams Morgan, and ends where one might expect of the line referred to as the Mount Pleasant line, in Mount Pleasant. It has a blog. (Okay, technically the blog is not by the bus, but the blog is named after it.) And now it has a song. No, not that song. (Although still love.) But this one, that DCist has helpfully embedded for you over here.