Without a doubt the most versatile workout device you own is you. You can manipulate yourself to add challenge to almost any exercise, no equipment neccissary. Even the basics can become horrible, gas-face inducing slog-fests with the right amount of creativity. See if you can add some degree of challenge to your basic warmup movements (squat, pushup, pullup, lunge etc.) the next time you see them.
Lucas knows how much more fun L pullups are.
Aneel, 'Relaxing' in a handstand.
Dial, midway to the finish.
See you at 6,