Muppet...

It's the same favourite as mine.. it's called Wellia Wellia walllye (phonetic)...

She stuck a penknife in the babie's head...
Welliea Wellia Waaallye
She stuck a penknife in the babie's head...
Down by the river sawwwwyeeeee

(ok, well, that's the version I always hear - and I never do hear the words properly as the fella that sings it has usually had a few...

Ella