If you have a father-in-law with a good sense of humor maybe give this one a shot. A Kentucky man pulled a prank on his father-in-law by telling him his doorbell camera could unlock the door of the home by scanning his eyeball. It's a pretty funny video to watch. 

You watch the YouTube user Tim Eberle's father-in-law approach the door, bend over and peer into the lens. He even pushed the doorbell and leans in closer to ensure his eyeball is being scanned. He eventually walks away with a defeated look on his face.

I'm not so sure Tim Eberle was looking defeated when he was able to watch this. As for how his father-in-law is handling all the attention since the Today Show picked up this clip, let's hope he has a good sense of humor.

Retinal scanners are a thing used for increased security as some cell phones use eye scans to unlock the phone, and some ATM's use them as well rather than a PIN number. According to Fleming Companies, retinal scans map the unique patterns of a person’s retina. The blood vessels within the retina absorb light more readily than the surrounding tissue and are easily identified with appropriate lighting, and is a highly dependable technology because it is highly accurate and difficult to spoof, in terms of identification.

It's kind of a brilliant prank, I wish I would have thought about doing this.