Step 1) Make some tea. Usually decaf helps most Step 2) Get some calming music (Vangelis is a pretty good pick for relaxation, especially Oceanic) Step 3) Try to take a small nap. If this is not possible, just lay back, sip the tea, and just feel the music. Or... DRINK WATER. EVEN IF YOU THINK YOU HAVE ALREADY HAD ENOUGH WATER, DRINK MORE!! You might be dehydrated.
This song helped me earlier today when I had a headache. [video=youtube;NMmMNyTwePY]http://www.youtube.com/watch?v=NMmMNyTwePY&list=FLwnKRzsVpzITJrLqYLk53pw&index=2&feature=plpp_video[/video]
Or, you could ask your friend to punch you really hard on the arm. Odds are, you won't be thinking about your headache anymore. Oddly enough, dancing relieves most of my headaches.