This joke is a tribute to us middle-aged who start losing their memory.
Henry, a middle-aged man, visits his middle-aged friends. While the hostess is busy in the kitchen, the host Pete chats with Henry in the living room.
Pete: "We went to a really nice restaurant yesterday?"
Henry: "Did you? What is it called?"
Pete: "Wait a minute... What is that red flower with thorns?"
Henry: "Do you mean rose?"
Pete: "Yes, indeed. Hey, Rose, what's the name of that nice restaurant we went yesterday to?"