Senile Dementia?

　　Today, a nearly 90 year-old patient visited my opd a week earlier than I expected. He has long been seeing me regularly, but he didn't have an appointment today. However, he asked me to give him injections of the analgesics consisting of hyaluronic acid into his bilateral knee joints.
　　According to his words, he, along with his wife, had been invited to a memorial ceremony held by the U.S. Navy, casually dropping the name of the Commander of the Navy and they had to visit Tokyo this weekend. He wanted the injection for prevention of pain from his knee joints for fear of the long walking.
　　He lives deep in the forest and is a mere common farmer. I didn't believe his story, but I wanted to joke with him saying "Is your destination really Tokyo? Isn't it Yokosuka?" He replied, "Yes, How do you know that?" I just knew that the naval base is located in Yokosuka City and had no idea about the memorial ceremony." However, I started to think that his story might be true.
　　You always have to keep away prejudices, I deeply realized. He was one of the rescuers of the U.S. aircraft accident that had occurred near here in 1952 and also one of the founders of the monument to fourteen U.S. soldiers who had passed away at that time. This year is the 60th anniversary. Sorry for the kidding, old man! You are right!

http://kumo.typepad.jp/weblog/2009/04/short-touring.html

(Vocabulary)
joke with sb ＜人＞をからかう
drop  [他]〈言葉・名前など〉をふと口にする, 漏らす
She casually dropped his name into the conversation. 彼女は会話の中で彼の名前をふと漏らした．
casually  何げなしに