With apologies to Mary Poppins, here's one in a similar vein that I concocted a few years ago.

Super hyper calculated Brexit dividend
If you keep on saying it you'll sound around the bend
Super hyper calculated Brexit dividend
If you keep on saying it you'll sound around the bend.
Um diddle diddle, diddle um, diddle ay x4

I’ve never been afraid to lie
Since I was just a lad
My father taught me how to fib
I lied like Jack the Lad
But then one day I learned a lie
That outranks all of those
The biggest lie you ever heard
And this is how it goes, oh
Super hyper calculated Brexit dividend etc

I travelled all around the world
And everywhere I went
I'd tell my fib and all would say
There goes a clever gent
When Rothermere and Murdoch
Pass the time of day with me
I tell my special lie
And then they ask me out to tea
Super hyper calculated Brexit dividend etc

So though I’ve got a dodgy plan
There's no need for dismay
I’ll summon up this mega-lie
Repeat it every day
I’ll tell it o’er and o’er again
For days and days and days
But when the ordure hits the fan
It won’t be me who pays
Super hyper calculated Brexit dividend etc