I've found one easter egg. Also when posting in this discussion please give hints how to get it and not a tutorial. (The easter egg I found is on the internet browser and it is a famous website that contains BILLIONS of videos)

Open the game and just let the chat go on and on and it starts getting funny

Here's a hint for a possible easter egg: The viruses remember each time you die/respawn (especially the 2nd virus).

a easteregg i know has something that has a face in it

there should be an itch.io Easter egg... so where like you could play the game in the game

I was disappointied that nothing happened when I went to freesound.org

Another one is facebook, and it even has a link to freedownloads.com on it, sadly you cannot click the hyperlink. xD

I clicked ALT+F11 apparently it skips the part when you are fighting