Tried sharpening a knife on the rough, unfinished bottom of a coffee mug for the first time. Can't believe it but it actually worked. It's not perfect but it's a workable edge. Haven't tried the top edge of the car door window yet or the ceramic element from a commercial light bulb.
What weird thing not designed for sharpening a knife have you found actually sharpens a knife?
What weird thing not designed for sharpening a knife have you found actually sharpens a knife?