that was the name i was called by in school (2nd to 10th class). the explanation everyone gave me and i later gave everyone for that nickname is that there were other sandeep's in school and they dint want to confuse me with them. at that time i readily accepted it and was even happy about it. not that i am disapproving of that name, but i can't, for the hell of me, remember any other sandeep's in my class in all those years.
in case you were trying to guess what bk means, it is bhimavarapu krishna