Aren't Grandma's fantastic, they are the unrecognised comedy geniuses of the world.
Mine wears a hearing aid, but even with it in, she tunes out of conversations, so we constantly have conversations like:
Grandad: "We're thinking of going and having a meal at that new restaurant in town."
Other family member: "Oh yeah, it's supposed to be very nice."
...ten minutes later, we've discussed everything about the restaurant and are on to something else...
Grandma: "That new restaurant in town looks nice, your Grandad and I are thinking of trying it."
Whenever anybody else mentions something shortly after we've talked about it the response is now: "All right, Grandma."
(N.B. Probably funnier in person, rather than written down)