ok,i did this as a joke to a freind's guild,and it worked.I got 134g 34s 52c and a bunch of items.
1. find a guild with a lot of people,higher lvls are good.
2.make a character named something similar to the guild master's name,but with "bank" in it.
3.wait for the guild master to go offline,then whisper someone in the guild to invite you to it.
4.say that you are the guild master and that this is the new bank
5.they send stuff to you!
if its been posted,delete