Okay, I’m back, at least I’m trying to be back. I don’t have the slang for the year figured out, but here’s something for today!
blackleg–a progressional gambler or swindler, especially a racetrack swindler. It goes back as far as 1771, but seems to be most comonely used after about 1821, throughout the century. In the beginning it was two words: black leg(s)but by about 1850 it was written as one.