A popular forum game that I've seen in several different forums. We start at 1000 and everytime a guy posts they add 1, while every time a girl posts it's -1. The Goal for the guys is the get to 2,000, while the girls need to get to 0.
I'll demonstrate +1 so 1001.
Edit: Girls won game 1, but now it is starting at 10,000 and girls have to hit 0 again, while guys have to hit 20,000! So let the games commence!