It's between you and your friend. The IRS used the account information that you gave them when you filed your tax return. What the IRS sends to the bank is not a check. It's an electronic deposit with the account information that you gave them. The bank deposited it in the account that was designated in the electronic deposit. Essentially the IRS and the bank followed your instructions as to where to send your deposits.
Some banks check the name on the electronic deposit, but they are not required to, and many banks do not check. Obviously your friend's bank is one that does not check.
