I was board one day and asked my brother, "What should I make in Blender?" He says, "Um ... A blender". Never until then had I ever thought to make a blender in Blender! Maybe it's cliche, but it was still fun.
The blender itself was based on the Blender logo. The hardest part was working with the glass shader and still getting good render times, but I made it work. Made with After Effects, Premiere and obviously Blender. Rendered in Cycles.