[quote=@Plank Sinatra]
'...And when she saw what she had done, she gave her best friend fifty-one.'
[/quote]

"Lizzie Borden took an axe
And gave her mother forty whacks.
When she saw what she had done,
She gave her father forty-one."

In reality, Lizzie Borden's stepmother suffered 18 blows. Her father suffered 11.

Assuming the fifty-one wasn't a typo I would guess it has something to do with the playing card tattoo (52 cards in a deck minus the one in the tattoo not including jokers).