Take a hip flask.
However if your company is, like mine, one of those *weird* ones that objects to its employees being trolleyed at their desks, what about amusing yourself (and I use the term "amusing" quite loosely) with DIY espressos. Essentially, mix whatever shitty instant coffee they have at your work with the absolute minimum amount of water to dissolve the granules, and swallow. Repeat until you have to be scraped off the ceiling. :)