People relate my nickname with secret accounts in the Swissbank. They're wrong, though I wish I had them :D.
It means reliable: I keep track of financial information and situations of my close friends, also used to keep "emergency fund" and car keys during parties (To make them stay on earth longer :D ).
It was just one of the parties and a guy called B. asked me about T's stored items from me. Jockingly: "Nope, swissbank doesn't give details about customer without their explicit permission" was the answer, so the nickname came.
FYI: Switzerland is neitral country and has been regarded as safe heaven during and after WWII, since it kept treasures from all the countries, even Hitler didn't dare to invade it. There's a rumour that he too had stored lot in there-and it's still laying in there without anyone's knowledge except the swissbankers. Guess all the governments and secret agencies couldn't force them open up the information. Every now and then when there's a conflict in world Swiss Franc (CHF) value increases, figure it out!