Do you sometimes put secret easter eggs on yr software for fun ?
Working on financial systems I cannot really do that (hidden code is a no-no when working with transactional systems), but I certainly enjoy them in environments that permits it.
Here is a nice one for Mozilla Firefox… type the following in the address bar (excluding quotes):
“about:mozilla”
I often include a hidden SQL Window to check directly the SQLite database I use in my projects.
It helps me to debug.
I always do. I’m also very vocal on my twitter feed, so you’ll usually hear about them there.
My latest project includes at least one reference to Bill Nye the Science Guy.
Back in the 90ies I wrote multimedia software with Macromedia Director (Lingo) and couple externals DLLs (mostly in VB6/Delphi) as plugins. These multimedia software were kinda Point-and-Click Adventures mostly playing in the Middle Ages. You can still find it here: http://www.amazon.de/Terra-CD-ROMs-Schatz-Tempelritter-CD-ROM/dp/3930818558
I will never forget these wild times, I was young, hungry and my team mates and me have had a bucket full of silly things we put into this software and our contractor never found. For example in castle of the Middle Ages there was a brick with an tiny yellow marker. When you clicked on the marker exactly, an Aircraft flew through the scene making loud noise… kind as strange as Monty Python movies 
This is 15 years ago… I’ve never have had a chance to put an easter egg in my database business stuff again…
Yeah, but they’re generally referred to as “bugs”.
I’ve been known to hide a few things here and there. I once heard a story of a developer proving someone had stolen their source code at an expo by walking up to their display machine and triggering an easter egg that revealed a picture of him.
“I was young and needed the money”, heard often.
Meanwhile, I’m no longer young, but I still need the money.
Ja Detlef but today I wouldn’t work through the nights or I would never ever sleep in office right next to my desktop. Today we all hopfully have more experience and work more efficient than back in the 90ies 
I’ve never done it personally, but this was one of my favorites as a kid:
What is Susan Richards doing while flying the Invisible Plane of the Wonder-Woman?
The only “easter-egg” I do remember I made, was a hot-key activated joke in the beginning of the 80’s, made in a turbo pascal for DOS or ASM (don’t remember) linked with my Clipper App. When pressed the hot-key sequence, the letters on screen started to fall, one by one, and accelerating, then all fell in a cascade suddenly, hitting the bottom and disappearing after. Any other key pressed after the joke finished restored the screen as it was before. As my colleagues used my software to work, sometimes I took over their PCs and pressed the hot-keys destroying their screens. The first reaction was “What!!! My computer got a virus!” then later “How did you do that? Tell me! Please!”. Then later after people blowing theirs own screens around for days, it became boring and I removed (don’t remember if my boss asked me, probably not, but I told them it was requested). 
Correction. beginning of the 90’s. Precisely 1991.
I was tasked by my development manager to “quietly” introduce an Easter egg into a large commercial application back in the mid 90’s that displayed a picture of the development and QA team when a certain hot key combination was pressed. Being young and somewhat naive at the time, I did, and it made it into the production release.
Eventually, the CTO found out about it, the dev manager feigned ignorance and I almost lost my job. Lesson learned, and that was the last time I did that…
When people try to cheat reading time limited QR codes by changing their system date, I put a message on the screen saying:
A Wrinkle in Time
Time Travellers can not read this QRCode. Travel back to your own time to scan this QRCode…
It appears you are a Time Traveller! Unfortunately, QuiQRun! does not work while travelling so you won’t be able to read QuiQRun! protected QRCodes until you return to your own time-line.
I think it’s a funnier way to point out to someone they tried to cheat.
btw A Wrinkle in Time is the header of this messagebox and is somewhat of an inside joke. It’s the title of an old children’s fantasy novel I used to read (http://en.wikipedia.org/wiki/A_Wrinkle_in_Time)
Don’t like eggs at all, since they come from the ass of a bird.
Second, I don’t understand what Easter has to do with eggs. Who has ever invented that nonsense ?
And if it were not crazy enough we put these in our buggy software and call that funny. Ha ha… .
See, this forum-engine doesn’t like the body part of the bird I am talking about, a little squeamish isn’t it. And funny too.
Not realy an easter-egg…
During my school period we had to create some little ‘programs’. Maybe ‘tasks’ is a better word. Non usable programs just for learning. Good learning stuff, but I found it boring at that age.
At some point I started making a copy of a character game that was very popular on dutch television in the 90’s (Wheel of furtune)
Each lesson again I spent some time on it.
In the 90’s there were already visual tools, like Delphi and Visual Basic, but at least on my school we still used the good old Turbo Pascal (dos). Without any images I had to creat the wheel by drawing polygons for each pie on the wheel, some colors, sound effects created by beeps in different duration, randomize and more.
At each moment the teacher came close I switched back to the task of that lesson. At some point my teacher found out I was doing something else. Instead of telling me to stop, he gave me the exclusive task to make it complete and I only had to implement all technics of the chapters in our book. The next time the school was having an ‘open house day’ my app was running in the classroom projected with a beamer. So newbies possible tought… “What a great school. Here we gonna make games!” But after they became students they start making the boring tasks as well.