Lady Macbeth — the blood stain

“Still alive, killing time at the cemetery Never quite buried”

Uncle Jerry compares the inability to bury this relationship, 'never quite buried', to Lady Macbeth's blood stain that can't be washed off, saying 'It's like that blood stain you can't wash off Lady Macbeth. It's just there all the time.' He uses this to illustrate the omnipresent, indelible nature of the relationship's memory.