Not quite sure from your wording but I think this is what you're asking:

If you have an account with a low level toon named Garfield that has RAF'd a second account with a toon named Odie... when Odie hits 40, he'd have 39 levels to grant to any toon 40 or under on the same account as Garfield. This is Blizzard's way of thanking Garfield for recruiting Odie. Whether or not you happen to be both Garfield and Odie or if you actually RAF'd a friend who played and leveled.