Rosie wanted to kill John, so she invited him to a dinner at her place.
They both had a dinner together, had wine and fresh fruits.
Rosie then insisted John to have a last fruit left behind.
Rosie said "That's a dark red sweet apple and I insist you to have it".
John said "No, you have it, there's only one left".
Rosie said "Let's share the apple then".
John said "Ok".
Rosie promptly sliced the apple with her sharpest knife nearly into two equal halves and shared it with him.
Soon after eating the apple John's eye rolled towards the celing and dead, but Rosie did not die.
Why was Rosie not poisoned after eating the apple?
Comment your answers down.