A Cess Pool is a term used to describe a collection of female acquaintances to be shared as a common resource among a group of guy friends.
To be eligible to be added to the Cess Pool, the female in question has to be of a decent standard, and should not be the love interest of anyone in the group.
The main purpose of adding females into the Cess Pool is to always have a group of female friends ready to be called upon by the group for any activities such as clubbing, drinking or even unadulterated sexual debauchery.
A: I just met a couple of cool girls over the weekend.
B: That's great, just add them to the Cess Pool and we can hang out this weekend!