Most terrifying sound

Three retired old gents, raconteurs all, were sitting around the National Geographic's Explorer Club, sippin' on some 25 year old scotch and spinning tall tales from their past, when the oldest asked, "What was the most terrifying sound they ever heard ?"

The first old man said, "I was in Africa and got separated in the bush from my guide and hunting party and suddenly heard a deafening noise, a herd of wild elephants thundering right at me and I had no place to hide."

The second gent said, "I was an air force fighter pilot and was flying from New York to London and was over the middle of the Atlantic Ocean when the jet engine on my plane began making the most sickening sounds I had ever heard anything mechanical make, like it was breaking apart and about to quit."

The third man, the one who had asked the question said, "I have the worst one of all. I was having an affair with this married woman that lived in Hollywood Hills and her husband surprised us, coming home early from an out of town trip, and caught us, naked going at it in their bedroom. I jumped up, ran to the window and tried to jump out."

The old man paused, was sipping a bit of scotch, when one the other two men asked, "Well, so what was the terrifying sound?"

He replied, "Just a minute. This is a little hard for me to relive."

After a short pause, he took a deep breath and continued, "Well I was more than half-way out the window but the woman's husband had grabbed me by the testicles as I was falling ! So there I was, hanging by my balls, and the worst sound I ever heard happened. It was the clicking sound of a man trying to open a pocket knife with his teeth!"