The hearing aid
Seems an elderly gentleman had serious hearing problems for a number of years. He went to the doctor and the doctor was able to have him fitted for a set of hearing aids that allowed the gentleman to hear 100%. The elderly gentleman went back in a month to the doctor and the doctor said, "your hearing is perfect. Your family must be really pleased that you can hear again."
To which the gentleman said, "Oh, I haven't told my family yet. I just sit around and listen to the conversations. I've changed my will three times!"