My boyfriends sister wants her grandma to hurry and die so she can inherit her part of the old womans millions?

My boyfriend lives with his paternal grandparents and they are millionaires. But they are very thrifty so they add so much each year to their money. Anyways my bfs sister is always asking him "Has grandma croaked yet?" or "damn when is grandma gonna croak I need money!" I think its so horrible and I really want to tell her what she has been saying but I don't know what to do. This stupid heartless bi*** is in her will and will inherit a good amount after my bf and their brother. Any help??