The Toaster in the Rock – Gears of War 2
In “The best laid plans” level from the Campaign there is a stairway that leads into a balcony that has a platform with a decorative block at the edge. If you figured out that you have to break it, you’ll find a steel plated toaster inside of it. If you push the bread in the toaster it will start to smoke and as soon as the toast pops up and Marcus or another character will shout “Who wants toast?”
This one is definitely the hardest object to find in a video game because it’s nearly impossible to imagine that by breaking that cement block you’ll find a toaster buried inside.