What story does George tell and how does Lennie react to this story?

Per Lennie’s request, George agrees to “tell about the rabbits,” which is Lennie’s shorthand for “talk about how things will be for us in the future.” George paints a picture of the future – a picture he has obviously painted countless times before – in which he and Lennie have their own place on their own farm and “live off the fat of the land.” He promises Lennie that they will have rabbit cages and that Lennie will be allowed to tend them. Lennie repeatedly interrupts George as he tells this story, but insists that George finish it to the end. Lennie is excited and hopeful.