If this is a serious question, I'll give a serious answer.
A fender washer is similar to a normal washer except that the matal disk is
much larger in proportion to the hole. In a normal 1/4" washer, for example,
the outside diameter is about 1/2". A 1/4" fender washer will have a 1/4" hole
in a 2" disk. Fender washers are mainly used in automotive applications, hence
the name. The larger diameter of the disk spreads out the force of the bolt so
the fender is not distorted. There are other applications around the shop, too.
One of them is if you're going through your miscellaneous jars of screws and
bolts to hold something together and your found bolt is too loose for the hole
and you need a washer to fill the gap, the fender washer fills the bill nicely.
Or, if you're using thin material and don't want to pull through the 1/4"
plywood, for example, it would have a similar effect as if used on an actual
fender of a car--it spreads the force of the pull between nut and bolt.
-Jim Gott-
San Jose, CA