Boys VS Girls!
This is a simple game. The count starts at 50. Guys want to get it to 0, girls to 100. To change the count, for guys, you post one down from the current count (i.e. 49, then 48, then 47, etc.) girls post one up from the current count (i.e. 51, 52, 53, etc.). Now, that doesn't mean it's just a race to get 50 posts (although that sounds interesting... hmm...) it means that if guys post three times, bringing the count to 47, the girls' next post would be 48. So, have at it!
Only one rule that no double posting- You need someone to post before you can post again. I'll start it off.