Why do I always feel so sick on weekends?

I don't know what it is but the past 3 Saturdays I have felt so sick and gross. I just don't understand. Maybe it is the air/water at work but I mean I was there today anyways. I had to do some laundry and I didn't have any quarters for the machine here so I thought I would give it a try. However I was not the only one with this idea and the machines were quite full. I finished my laundry but my socks weren't completely dry... I hate it when that happens.