"A Shot in the Heart" joke

Mildred was a 93-year-old woman who was particularly despondent over
the recent death of her husband Earl. She decided that she would just
kill herself and join him in death.
Thinking that it would be best to get it over with quickly, she took
out Earl's old Army pistol and made the decision to shoot herself in
the heart since it was so badly broken in the first place.
Not wanting to miss the vital organ and become paralyzed, she called
her doctor's office to inquire as to just exactly where the heart
would be.
"On a woman," the doctor said, "the heart would be just below the left
breast."
Later that night, Mildred was admitted to the hospital with a gunshot
wound to her left knee.