How many coffee cups should one person own?

This is what I have at work...yes count them 6....WOW 6. Does anyone else have a fascination with coffee mugs? I find myself at Starbucks looking at all of the cups on sale before I even order my drink....

So I have to do something, right? Well this is what I will keep at my desk...one for coffee and the other for water.....the rest, I guess....I will just take them home....