If someone you do not recognize has requested that you be their sponsor you may simply reject the account. It is not uncommon for a sponsored account holder to mistype the user ID of their sponsor when requesting that their account be approved.
Rejecting an account you are unfamiliar with will deny access to AKO/DKO for the requestor. If a guest user has a legitimate need for an account and accidentally entered your account name they can always call the help desk for assistance in changing their requested sponsor.
For more information about your Sponsor Management Console and approving or rejecting accounts please see How to manage your sponsored accounts.