The Royal Plural.
I've always used it in my own language because I was raised in Awadh(Lucknow). Had to take a lot of stick as soon as I moved to schools in other cities =D
I cursed my luck for having been born in pretty much the only city where it was the norm among the community.
That is why I so gladly embraced English later in my early years, at least in English I said 'I' instead of 'We' =)