aHAhahhahAHHahaHaA!!!
*ahem*
It's fun :3

Remember QWOP? Now imagine the limitless potential of a full set of muscles to control. It might be a bit more difficult to learn than most other games, but the feeling of successfully pulling off a manoeuvre is very satisfying. Even when something does go wrong, which happens more often than you might expect (it's a game where most of the modes involve turning your opponent to mush) the hilarity of the ragdolls and the physics engine keep it interesting.
Also, it's free and has a rather small file size. Just pick it up! :D