sqlite - How can I order in group but randomly?

Let`s say I have a table with one column being:

Letter  
A
B
B
C
A
A
C

I'm trying to make a query which would return these letters in order but in a random order, like first all the C's then all the A's, etc. Example:

Letter  
C
C
A
A
A
B
B

So the letters would show up together, but in a random order each time I queried it. How could I accomplish that?