Emptying a keg is much easier than filling it because people are always willing to help!
Depending on the design you can fill them with one of three methods.
1. Cut a hole in the top, fill and then plug/weld
2. figure out how to dismantle the valve system and fill it through the top.
3. Easiest but slowest is to use a screwdriver to depress the rubber seal and then run water into the valve.
Now if you need to aquire a keg you can sometimes buy empties from distributors or you can hire one and not return it. You'll lose the deposit but thats what it's for.
Now to empty your keg in true CF fashion i suggest the following workout.
10 thrusters 40kg
drink one glass beer
winner is the one who completes the most rounds before meeting pukie.