UK: Bank account numbers are public-ish and it's normal to give them to your friends so they can send you money (it's not normal to buy from an actual shop that way). Jeremy Clarkson made a point of giving his out on national TV. The one way to get money out of someone from those numbers is a direct debit, but as sibling comments have said the other end of those can only be a merchant account and the individual is easily able to reverse them.