"The game of Counterstrike is an interesting one. It is a realistic simulation of a terrorist/counter-terrorist combat situation, assuming that real terrorists actually have no intention of carrying out their mission, and instead only want to lure stupid uniformed counterterrorists to various locations and kill them. You see, most terrorists want to blow things up or take civilians hostage in order to scare people, but Counterstrike terrorists are the soft, fuzzy kind of terrorists. They really don’t mind if you walk away with their hostages or defuse all their bombs, just as long as you don’t crouch in one place while you do it."

http://www.somethingawful.com/articles.php?a=395

actually, all of their guides are funny:
Survival Guides

Which, in turn, is why it's funny.