well I think its all been said...
anything with a thick razor or metal incline of some sort
or a knife sharpener...
Look around your kitchen. A lot of appliances have knife sharpeners on them for some odd reason. Heck, my electric can opener has one [for reasons unknown]
Also, look where your parents keep the knives. There might be a long metal rod attached to a handle. You can use this to sharpen your knife.
u go to a wal mart er somthin and buy a knife sharpener and if you can slide the blade across another knife why r you askinf this q anywa?
eat it O_o
oh wait no..
I suck at advice -_-
Stones and steels work great for keeping a fine edge on cutlery. Hold the knife at about a 15 degree angle to the stone or steel and draw it to you, or for beginners, motion like cutting away from you on each side. A few strokes will keep a keen edge and they always cut safer and easier when sharp. It is the dull knife that cuts people because of the added force needed to make it work. A sharp knife will easily cut a tomato with very little pressure and what a joy it is!
yea like what melissain said or use another knife
or a blade
liek a razo rbladde
a knife sharpener, or if your cheap, a flat rock.