I tried several different ways to deal with the problem, including buying everyone their own cups and using paint to write names on them . It didn't work so well. If their cup was in the wash, they would get out new ones and end up with a "hundred" of cups again.
Finally, I hit a solution that works wonderful for our family.
Now when they get a new cup every morning, they put their personal band on the bottom of the cup. This way, they know which one is their cup all day. At the end of the day, they take the band off and put it in the silverware drawer. The next day they put the band on a new cup. Now we don't have to worry about the bands getting lost, the cups needing to be washed, or not knowing which cups is mine.
It works perfect and is so easy!
What about you? Do you have a way to keep cup clutter under control?