Years ago, I used to be a breadmaker at a bakery. During the summer I would come to work at midnight, and it would be 95F...before I ever turned the ovens on! After turning the ovens on, it would be well over 100F...for hours on end.
So what I started doing was go into the bathroom (I was the only one there), remove my shirt, rinse it in hot water (yes, hot...I'll explain), wring it out really well, and put it back on. The evaporation process instantly made it feel about ten degrees cooler. When my shirt dried out enough that I started feeling hot again...I simply repeated the process.
The reason for hot water instead of cold is that it's less of a shock to your body. Originally, I used cold water...but you know how much fun it is to put a cold, wet shirt on...? Yeah. If you use hot water, it goes on fairly comfortably (no temperature shock) and due to evaporation, cools itself down very quickly.
I still use this "trick" at my current job...and it works beautifully!
