You can sponsor an upgrade for anyone. As long as this is for free you are o.k.; you don't need to know that person necessarily. Of course UA is sensitive to this, so folks have gotten into trouble when they e.g. gave them to charity auctions for example since the 'buyer' paid for them, just not to the holder of the cert.
You don't give them away, you log into your account and upgrade someone else ... I do it all the time, never an issue. Family, friends, co-workers ...