Old Lady- "Well, you see, my husband was in the war and lost both eye balls in a terribly gory pencil throwing accident"
Old Man- "But luckily, my wife here had both eye balls, and gladly lended me her left one. In order keep the empty socket from getting infected, we have to rub triple antibiotic ointment into the membranes."
Old Lady- "You senile fart, I'm not your wife! I'm your sister!"
Old Man- "Then was were you doing to me with your empty eye socket last night? I could have sworn you- ohhhhhhh...."
Old Lady- "....Ahem.... Er, deary, what a lovely Persian rug we have!"
Old Man-"That's not Persian."
Old Lady- "That's it, I've had it!" *jabs old man in empty eye socket*