you're not sleepy as you seem...

Today is one of those days where I just can't shake the sleep off
Just like that nescafe mycup commercial where the guy has the mattress stuck on his back (this may be only an arab thing) but...
two and a half hours into the work day I'm on my second cup of coffee... still waiting to wake up.
Why won't my mattress fall out of the window?

During college, when the sleep attempted to gain control over me during classes (usually econ), I used to do full body flexes. I would flex every muscle in my body for as long as I could stand it- over and over again- to stay awake. It worked. I just hope no one was looking at me, I probably made funny faces.
Somehow I don't really think that would work as well now. Because, although it kept me awake, it was usually the only thing I was thinking about the whole time. Fine for econ- who needs econ anyway?- but probably not the best technique for work. I have to at least look productive.
So when coffee doesn't cut it, and I can't hide myself away for a nap, how do I stay awake at work?