Will Fly: When we were kids at school, at the height of the famines in Africa, we used to sing a parody of the Heinz beans ad:

'A million Biafrans every day,
Open a can of beans and say,
"One for you, and one for you, and...'"

Tasteless or what? The thoughtless cruelty of kids...

Indeed. We sang that too,

And this one:

Hush hush, whisper who dare
Little boy at the foot of the stair
With blood on his hands
And fur on the mat
.....Christopher Robin castrated the cat

And there's Doc Cox, AKA Ivor Biggun:
I'm A Wanker