Envy of your unborn descendants who will live in the future and have access to awesome future technology.
Person 1: Someday they'll invent chips you can have in your head that can access the internet.
Person 2: Oh man I want one.
Person 1: It won't be for a hundred years though.
Person 2: Aww, man! So those lousy future people will get to do it but not me? Lame!
Person 1: You have a case of grandchildren envy!