Speaking from practical terms, I've put a few Easter eggs in various projects since the late 90's, but it's always terrified me that my dumb little fun thing wo

Speaking from practical terms, I've put a few Easter eggs in various projects since the late 90's, but it's always terrified me that my dumb little fun thing would cause the crash of a mission critical task. No oceanographic scientist from a long planned expensive research mission needs to find out that the data is bad due to some "funny stuff". But speaking in fun terms, probably the best fun I ever had with it was putting little "Waldo" images in levels I developed as part of a popular online shooter. It was my online nickname at the time, and it was a lot of safe entertainment, both for me and for the players.