This is a funny & quick routine right out of the Tom-Foolery bar show.
 
The audience notices your eye seems to be bothering you. You reach into your eye and remove a contact lens. But wait! The lens is huge it is 1/8 inch thick and has a two inch diameter.
 
You wipe the lens clean while everyone is laughing and put it back into your eye.
 
Outrageous but very convincing magic. Easy to do. Comes Complete.