Isn't there a really rhyme that goes something like :

My name is Jack, tidilly-ack, tidilly-ack
I'm a necrophilliac, tidilly-ack, tidilly-ack
I get frustrated, tiddilly-ated, tiddilly-ated,
When I see them get cremated

It makes me chunder, tidilly-under,tidilly-under,
When I seem then 6 feet under, tidilly-under,tidilly-under,

Last week my ....? Jack, tidilly-ack, tidilly-ack
....?
It made me .... ?
When I heard his pelvis crack, tidilly-ack, tidilly-ack

I lived with two girls at Uni in Newcastle and they learnt this on their walking trips to the Cairngorms. I've never been able to find all they lyrics - the above are the only bits I can remember from their singing. When they sang it one would look guilty and the other would sing it with mischievous lust.