Todays edition is brought to you by Eric Cressey out in Hudson, MA.
What it is: Overhead-Keg Reverse Slideboard Lunge.
Why it is sick: About a billion different reasons. Any lunges are good; single leg work is often an overlooked aspect of a training regimen. Utilizing the slideboard really forces you to focus on using your front leg only, and not getting any kick from your non-working (back) leg. The overhead lift really challenges your thoracic spine mobility and your shoulder stability; two very important pieces to the good posture-puzzle. Depending on your mobility level, it will also provide a good challenge/stretch to your hip flexors, something a lot of people need after sitting in their office for 9 hours. To say that this is a total body exercise would be like saying the Titanic had a little leak in the side.
You don't really NEED to hold a keg overhead; but it looks pretty awesome. Any external resistance will suffice, although the keg adds a few challenges. Because of its awkward shape, the weight is not going to be centered through the middle of your hand; it creates a very different center of balance. In most commercial gyms you can find something else to hold overhead; a dumbbell, barbell, medicine ball, weight plate, the 95 lb guy doing endless sets of 15 pound bicep curls. Your choice.
Now go do it!!