I am not a journeyman electrician, but I've had my fair share of get-what-you-want experience(Hence the name Makeshift in my username).
This is for informational uses only, demonstrating voltage potential in AC systems.
You would need to find his breaker, the opposite phase, and the common ground for the system(Dist, not audio).
First, turn off the main breaker, taking the whole system down. Flip all the breakers except the breaker corresponding with his branch. That's the simple part. Remove the common ground (ALSO CAN BE NEUTRAL, but either way a 0V reference voltage potential, one is dedicated ground, and the other is the centertap of the distribution transformer's secondary, which is also grounded at the tap, usually to the case, also being the opposite high voltage terminal, so that the current will flow from the high voltage primary lines, through the transformer, to ground, and then hooked to house ground to sustain a common 0V reference point) that only being if they are not wye config, which is 3 phase, but it can be the case)
Hook the neutral wire heading to his branch up to the opposite phase, and make sure the ground for that system is not directly grounded via the bus bar. The problem with this is that it might take out everyone that is on the same target phase at the same time if you are not able to isolate and separate the corresponding neutral line, since now, to the people that do not have their breaker on you have a 120V signal on the neutral, and a 0V signal on the hot, since there is no breaker for neutral, destroying everything on that whole phase //content.invisioncic.com/y282845/emoticons/youreawesome.gif.a27e190c662afa8e2be5686b27bd1659.gif
The problem lies in the sharing of the neutral line with ground in some cases. If you are able to isolate that breaker's neutral, you will apply 220V to the whole breaker. Did I mention to turn off the main breaker?
Again, do not do this. At all. I just put this out there to make sure I had it right in my head. Just call the police in the late night if he still has it playing. //content.invisioncic.com/y282845/emoticons/crazy.gif.c13912c32de98515d3142759a824dae7.gif
PS: Distribution transformers are fun. I have a 15kva 7.2kV one in my back yard that I used to power my 25kva tesla coil with. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif I used 1/2 the what-now-is-primary turns with 240V to double my voltage/turn ratio, and get 14.4kV output.