I will take a guess but it would be helpful if you could provide more detail on where you saw the words. There is an American cartoon character whose name is Scooby Doo. He is a large dog who can talk, but not very clearly. When he says his name, it comes out as "Looby Loo" or "Rooby Roo" in subtitles.

Now can you tell you where did you learn this?

Crap! This is the first time I heard about this, and my name (real name) is luby lu... It's originated from a British children's tv programme I believe.