OK, 'Hey Dude' has obviously been a parody of Hey Jude before, but the concept here is that the singer/s have forgotten said person's name.
So, references to: calling them the wrong name, trying that trick where you ask for their number and spelling of their name (only they say its spelt as normal or some such), knowing them for ages, resorting to physical descriptions/participation in events as identifiers
The Naaa/na/na/na/na/na/na bits could be the singers trying different starting bits of names uncertainly eg. baaar/car/ta/ma/ja/ra/huh?

 

Hey Jude don't make it bad                                                                                                        Hey Dude I feel so bad
Take a sad song and make it better                                                                                            Wish I knew how I could make it better
Remember to let her into your heart                                                                                            -I can't- Remember your name in full or in part
Then you can start to make it better                                                                                            How your name starts or the first letter

Hey Jude don't be afraid                                                                                                            Hey Dude I feel ashamed
You were made to go out and get her                                                                                         Been in the same grade since two thousand and seven
The minute you let her under your skin                                                                                       The minute we met you said your name
Then you begin to make it better                                                                                                It left my brain three seconds later

And any time you feel the pain, Hey Jude, refrain                                                                          And every time you say my name, Hey Dude, refrain
Don't carry the world upon your shoulders                                                                                    From putting your hand upon my shoulder
For well you know that it's a fool who plays it cool                                                                        For well you know that I'm a fool who plays it cool
By making his world a little colder                                                                                               While letting our friendship get even older
Da da da da da
da da da da

Hey Jude don't let me down
You have found her now go and get her
Remember to let her into your heart
Then you can start to make it better

So let it out and let it in
Hey Jude begin
You're waiting for someone to perform with
And don't you know that it's just you
Hey Jude you'll do
The movement you need is on your shoulder

Na, na na na na na na,
Na na na na, yeah

Hey Jude don't make it bad
Take a sad song and make it better
Remember to let her under your skin
Then you'll begin to make it better
Better, better, better, better, better, Yeah,Yeah,Yeah

 

Na na na na na na na,

Na na na na,

Hey Jude

 

etc