Z could also be "I am a Zider drinker".
DMcG: there is a reference to the Zuider Zee in a song for which I acn't recall the title (Possibly "The windmill's turning") The verse:

In Holland there's a smiling face
Beside the Zuider Zee,
With eye so light, the blues so bright
They shine across the sea
Her eyes forever to the sun,
A tulip in her hair
And when she's sad she starts to sing
To lovers everywhere

CH:
The The windmill's turning
My heart is yearning
In dreams I'm bringing to you our love refrain
The The windmill's turning
My heart is yearning
And in my heart dear, I know we'll meet again

Nigel