why does this unpacking work

[John Salerno]

I'm a little confused, but I'm sure this is something trivial. I'm 
confused about why this works:

 >>> t = (('hello', 'goodbye'),
      ('more', 'less'),
      ('something', 'nothing'),
      ('good', 'bad'))
 >>> t
(('hello', 'goodbye'), ('more', 'less'), ('something', 'nothing'), 
('good', 'bad'))
 >>> for x in t:
	print x

	
('hello', 'goodbye')
('more', 'less')
('something', 'nothing')
('good', 'bad')
 >>> for x,y in t:
	print x,y

	
hello goodbye
more less
something nothing
good bad
 >>>

I understand that t returns a single tuple that contains other tuples. 
Then 'for x in t' returns the nested tuples themselves.

But what I don't understand is why you can use 'for x,y in t' when t 
really only returns one thing. I see that this works, but I can't quite 
conceptualize how. I thought 'for x,y in t' would only work if t 
returned a two-tuple, which it doesn't.

What seems to be happening is that 'for x,y in t' is acting like:

for x in t:
     for y,z in x:
         #then it does it correctly

But if so, why is this? It doesn't seem like very intuitive behavior.

Thanks.