In the song "Blue Jay Way" from the Beatles, we've got the following lyrics :
Please don't be long
Please don't you be very long
I'm (obviously) not a native English speaker but the first sentence seems right to me but the second one seems pretty weird because of the subject of the imperative sentence being explicitly given.
Is the second one just as right as the first one? Is it just a songwriter trick to get the good number of syllables? Is it something specific to the scouse?
Does having an explicit "you" change anything in the meaning? Which one is the most usual?
(Also, one can find the same king of difference in "Don't ever change" :
So please don't ever change
Now don't you ever change )