Microsoft launched Windows Insider Program for developers, enterprise testers and the "technically able" to test new developer features on pre-release software and builds to gather low-level diagnostics feedback to identify, investigate, mitigate and improve the Windows 10 operating system
It was announced on September 30, 2014, along with Windows 10
In the development process of the Windows 10 "Anniversary Update", which was released on August 2, 2016, Microsoft Insider Team "blessed" the Insiders with a display of several funny gifs which could be shown when a web page would not be found by the Microsoft Edge web browser
The website hosting server will typically generate a "404 Not Found" web page when a user attempts to follow a broken or dead link; hence the 404 error is one of the most recognizable errors encountered on the World Wide Web
Microsoft Edge web browser initially did not display "404 Not Found" instead "Hmm, we can't reach this page" message was displayed...
... but Microsoft Insider Team decided that this message was too boring and they replaced it with several funny gifs which were accompanied with funny messages...
Music: TechSmith