On a milling machine at work. It had a digital readout for the slide positions and on a whim I pressed the "." Button about 10 times. The display did a flashing dancing thing and went into a diagnostic mode where the buttons made different patterns on the display.

That all the StarCraft units had hidden voice lines when you keep clicking on them.

This corpse in Lunacid:

The problem is when it happens you often don't even realize its an easter egg. I honestly can't remember any but I know I have seen wierd things and talked with people and it ends up being an easter egg.

The Time Bangle in the first Devil May Cry. For years I had a walkthrough on how to get it in some gaming site. In the past decade or so it's disappeared from there but YouTube has anyone covered now.

I discovered how to get the Tetra Elemental accessory in FFVII without the Battle Square.

My husband found the 2nd Ribbon, up on the cliff, by himself. It was never mentioned in the guide books (pre-internet)

Not an Easter egg per se, since it's an intended item in the game, but very obscure and easy to overlook.

I found the Karasawa rifle in one of the Armored Core games for PS1 (either AC 1 or Master of Arena, played both a LOT). It's easily one of the best weapons in the game, has an iconic look, and is wielded by the final boss (who is hard af to beat, btw).

This game was ahead of its time when it came to multiplayer. You could save your custom mech onto your memory card, then plug it in to your friend's Playstation and go 1v1 against their custom mech.

I remember all my friends' reactions when I loaded up my mech and they started freaking out wanting to know how I unlocked it. I didn't know it was possible to miss, couldn't remember how I unlocked it, and couldn't do it again when I tried on a new save. For a little while there, I was the envy of the neighborhood with my final boss rifle. I finally copied my save to my friends so they'd quit blaming their losses on not having it

I found a weird, grenade-looking thing in an out-of-bounds section of the first area of Borderlands 1. It was under a cliff with no collision and just floating a few feet off the ground.

In Krom's Canyon (also Borderlands 1) there's a cave hidden way up on a cliff at the very start of the area. If you grenade jump up there, about half way in, the floor of the cave doesn’t have collision, but you can carefully grenade jump further in. At the end of the cave, there a single, ordinary loot container with a single, ordinary stack of cash in it.

The floor has no collision. The only way to loot the cash is to grenade jump, open the loot container as you fall out of bounds, then respawn, get up there again, then grande jump and grab the cash as you fall out of bounds again.

Of course, nothing special happens if you do this. Both of these discoveries are probably just portions of the map they started working on, then abandoned for whatever reason, and just never went back and deleted either because they forgot it existed, or they figured no one would ever see it.

At the time, I was convinced I was on to something. This was around the time the devs said there was an Easter egg in the game no one had found yet, so everyone was on the hunt.

The real egg ended up being a QR code textured onto a pamphlet in a stall somewhere. Can't remember exactly, but I could probably walk there if I booted up the game again.