Push-ups are one of the most tried and true methods of working out.  One-armed push-ups are considerably harder, but when you start doing them with a Rubik's Cube in your other hand, you've pretty much entered Batman levels of bad-ass.

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First of all, don't go all Monroe on me just because a dude has his shirt off.  Second of all, HOLY CRAP!  I couldn't solve a Rubik's Cube sitting on my couch, let alone in under a minute while doing one handed push-ups.

Source: Fark