A stand-up comic gets a gig to perform at a old age home.
Soon into his act he notices that most of the old people there are pretty out of it so he tries to tell the same joke twice and people still laugh cos they have already forgotten that they just now heard it.
So he gets a kick out of it and keeps telling the same joke for half an hour and towards the end of it he notices that one old guy is staring at him. He finishes his half hour and is about to leave and that old guy approaches him.
The comic is a bit nervous that the old guy is gonna confront him about what he just did. He braces himself for some uncomfortable confrontation and the old guy ask him “How do you remember all those jokes?!”