What's in a name?

Everybody likes to be called something by their offspring.  I like 'Mama' when very young then 'Mummy' and will eventually settle for Mum when they deem Mummy too babyish.  I secretly like Mama and Mummy, I do.  One of the many super things about having small ones is being called Mummy, so why, yes why, does The Toddler  with a very limited vocabulary not only insist on calling me 'Mum' totally bypassing Mummy but has also perfected that teenage 'Muuuuuuuuuuuuuum' when he wants something?

You'd be surprised as to exactly how superbly expressive and conversational he can be, you know, what with the whole lacking in the actual words department.

Me: 'H...'
The Toddler: 'whaaaaat?!'
Me: 'please come back in here'
The Toddler: 'whhhhhhhy?'
Me: 'because it's safer in here darling'
The Toddler: [Huffs and sighs..loudly and dramatically]