Some of these were intentional, and some were not.
Here are 3 of the eggs that I know about in Microsoft Office:
We had a set of incredulous meetings but it became clear they weren't budging.
I also had to make illustrations for tooltips that we thought would be useful since there weren't resources to create those either.
This fountain is historically important to the Office team.
Yes, it was absolutely as weird of a tradition as it sounds.
I’m not sure if anyone on the team ever looked close enough to the tooltip to notice what it was!
This is one I am less proud of. When we created the new Ribbon user interface for Office 2007, there were a lot of people internally in the Office team who were... let's say... disbelievers.
It needed a big slide and then a set of small slide thumbnails at the bottom.
This required making more fake slide content, and we knew that these would be so small once shrunk down that no one could read them.
Ok, this one was totally inadvertent. We wanted a new Reminder sound for Outlook 2003, but again, the team who would have made such a sound "didn't have budget."
Did I know my name was embedded in Microsoft Office? 😨 I was worried.
So an embedded name looked a lot like a security breach.
In today's world, of course, easter eggs are in vogue again, from April Fools software pranks that are all the rage to "404 Not Found" games and similar embedded funlys.
Human creativity always finds a way out!