Depending on whether you heard the Don McLean version or the Madonna version of "American Pie", I have left out or added verses, because I couldn't think of any more rhymes, but didn't want to leave out what I had already written. Enjoy, haters of Mary Sue.

A long long time ago
I can still remember
How the fanfic used to make me smile
And I knew that if I had the time
My tales would have a chance to shine
And maybe I'd be happy for a while
But the constant badfic made me shiver
With every one the 'net delivered
Bad news every mouse click
I couldn't take one more fic
I can't remember if I cried
When I read of Draco's fifteenth bride
But something touched me deep inside
The day the Sues arrived
So...

Bye bye Mary Sue, you must die
There's no-one stranger, you're a danger to our lives and that's why
Them good old girls from Potterbadfic arrived
Singing read that and your braincells will die
Read that and your braincells will die

Fanfiction-dot-net is tough
And we don't want your Suey love
Though your fangirls tell us so
Harry Potter hates your rock and roll
And there's too much garbage at the Pit of Voles
You really need to proofread real slow
Well I know that you like Severus Snape
'cause I saw you clawing at his cape
You both kicked off your shoes
And he threw them straight at you
I was a lonely teenage Potter fan
I thought Dan Radcliffe was my only man
But I wanted to kill the whole fangirl clan
The day the Sues arrived
I started singing

Bye bye Mary Sue, you must die
There's no-one stranger, you're a danger to our lives and that's why
Them good old girls from Potterbadfic arrived
Singing read that and your braincells will die
Read that and your braincells will die

Harry would rather be on his own
Than with these girls driven by hormones
Please kill them now, they're hurting me
We've suffered She-Snake and Dragon Queen
Written by twits on cheap caffeine
That really isn't how it ought to be
These Mary Sues all get us down
Of all badfic they wear the crown
The evil things must burn
To Hell they should return
When the last one popped out of thin air
With her purple eyes and her perfect hair
We acted as if we didn't care
The day the Sues arrived

Bye bye Mary Sue, you must die
There's no-one stranger, you're a danger to our lives and that's why
Them good old girls from Potterbadfic arrived
Singing read that and your braincells will die
Read that and your braincells will die

I met some girls who sang the blues
And I told them they were Mary Sues
They flamed me and turned away
I saw the fics at Qanonreip
And I wept for Harry, Ron and Snape
The beta readers didn't want to play
And in the streets the fangirls screamed
The slash fans cried and the filkers dreamed
But not a word was spoken
The canon all was broken
And the writers I admired the most
Ran off when they were flamed to toast
They caught the last train for the coast
The day the Sues arrived
And they were singing

Bye bye Mary Sue, you must die
There's no-one stranger, you're a danger to our lives and that's why
Them good old girls from Potterbadfic arrived
Singing read that and your braincells will die
Read that and your braincells will die