Who the Hell is Debbie?

My son has some language delays.  He's very smart at figuring things out, and he understands pretty much everything we say.  But his own talking hasn't come along quite as fast, so we are working on it.  He is supposed to be seeing a speech therapist, but she hasn't exactly been showing up.  I guess she doesn't know what I do for a living, but she will when I ask for compensatory services. 

My son IS talking, even stringing some words together.  He says "Mama", "Daddy".  He knows what a "beetle" is, and knows lion, cat, dog, bird, alligator, hyena, cricket, and weirdly, antelope.  He's even said a very close approximation of 'cicada', close enough for me to understand what he was saying!  He knows 'eat', 'poop', 'go', 'car', 'circle', 'apple' and most popular is 'cookie'.     Zane has not EVER said 'no' or 'yes'. 

If my son can't say a word, he often makes an approximation.  For instance, the word elephant is 'e-hee', and his word for 'worm' is 'mmmm'.  Waffle is 'wa', water is 'wa-wa'.  These have persisted even though we always say the correct word to him, so I have to believe that is developmenta.   Then there is 'spider'; Zane's word for that is 'bee-ya'.  I imagine that there's a logic there, but so far I haven't been able to figure it out.

Grandma is 'Nia', and Grandpa is 'Paw-Paw'.  His Aunt is 'Auntie', and his Uncle is 'Uncle'.  He says 'Ty' for his cousin Tyler, and 'Maggie' for the dog, but he cannot say Tristan or Courtney at this point, and he appears to be trying to cover it up by smiling cutely or saying gibberish.  Because that's how he rolls.

When my son acquires a new word, we sometimes have to scramble to figure out where he heard it from.  We learned that his Auntie says 'dammit!' a lot, because Zane started saying it.  Recently, my son has started saying bye-bye and hello to Debbie.  He says it consistently, very clearly.  The only problem is that we don't know anyone named Debbie.  No relatives, no friends, no acquaintances.  Zane doesn't act like he's speaking to an imaginary friend, so I have to believe there is a reason.  It's not necessarily a specific person--at one point my husband was Debbie for the day.    The ONLY thing I can think of is that Zane has heard my brother call Larry 'Dub'-short for the letter W(I have no idea why my brother does this).  But that's stretching it. 

If we meet someone named Debbie, we're set.