Every year, the tech industry puts out sophisticated April Fools' Day pranks designed to look too outlandish to be real. But technology is advancing at such a rapid pace that one person's joke is another person's next big product.

The best example might be Adyen's Face ID, which pretended to use consumers' faces for authentication. The idea, as explained in a video from 2012's April Fools' Day, is that a consumer would stare into a tablet's camera and allow software to scan his or her face to initiate a payment. The customer then approves the payment with a "thumbs up" gesture.

Compare this to the Eaze app announced in February. Instead of biometrics, Eaze combines Google Glass and Bitcoin in a system that requires a Google Glass-wearing shopper to stare at a merchant's tablet, let the Glass' built-in camera scan a QR code on the tablet to initiate payment, and then approve that payment with a gesture (in this case, a head nod instead of a thumbs up). It sounds a lot like the Adyen system, but if Eaze is a joke, it has not admitted it yet.

Here's Adyen's 2012 April Fools' joke:

And here's Eaze's product demo:

It may seem goofy, but Eaze is one of the most obvious ways to use the Google Glass headset's QR code reading ability for payments. The other option, which might be more practical while Glass is still in limited release, is to let merchants use the headset to scan QR codes from a customer's phone. LevelUp has tested this approach.

And some mobile wallets, such as those from Square and PayPal, have long used the customer's photo as part of the authentication process.

Speaking of Square, the mobile payments company was part of an April Fools' joke last year wherein it announced a merger with Box, a file-sharing service, to become a new company called Polyhedron. This was a joke on the companies' names, but it was slightly prophetic.

The label "P2P" can be applied to both file-sharing and payments, and Square has been working to step up its P2P payments game throughout 2013. These moves, including the formal launch of Square Cash, culminated in an acquisition – Square's purchase of Evenly, a social payments company that launched just a year earlier.

Sometimes, April Fools' jokes don't invent a new idea as much as they revive an old one. Such is the case with PayWag, Barclaycard's imaginary payment system for dog owners.

As absurd as it sounds, PayWag would be right at home with Wag Bank, a recent attempt at developing niche banking services for pet owners. Wag, along with other long-dead niche banks for women, BMW drivers and David Bowie fans, tried to add non-banking services to appeal to a very specific audience. Wag would have also doubled as a virtual "dog park" with social networking tools. A 2001 version of this idea, Petloversbank.com, offered checks with an image of the customer's pet.

There are a still a few April Fools' jokes out that have yet to be materialize as reality, such as depositing cash through a smartphone's camera. But perhaps in a year or two, someone will figure out how to transform those jokes into real technology.