That is just silly. "Killer" is a total earworm.
On a black day in a black month at the black bottom of the sea
Your mother gave birth to you and died immediately...
'Cos you can't have two killers living in the same pad
And when your mother knew that her time had come
She was really rather glad.
Once that gets in your head, it just doesn't go away. But when I sing it to myself before I go to sleep it gets condensed to "You know when your mother died giving birth to you, she was really rather glad. Because you can't have two killers living in the same sea"