How to have fun on a boring Friday afternoon at the office:

IM your buddy a few cubicles away. Ask them if they're busy. Immediately prepare your next message: "INCOMING!!!!". As soon as you get their reply, hit send. Then throw one of the dozens of foam balls you've picked up off of  schwag tables. If you time it JUST right, they'll read your message at the same instant their eyes register an object approaching them on a collision course. Hilarity ensues!

This is probably really funny if you work in a callcenter and you are very, very bored.