Christianese is the language spoken by Christians. It makes no sense to anyone unfamiliar with biblical texts, but earns you major points in the eyes of other Christians, because it means your words are hella holy.
Common examples include: old man/new man, unblemished lamb, fruit of the spirit, washed in the blood, and let's not forget the ever popular born again.
Christian: Brother, I felt like I was really backsliding, so I crucified my old man and put on my new man, and now the fruit of the spirit is evident in my life!
Non-Christian: What the hell did you just say? You speakin' Christianese?
A coslap is what happens when a boy and a girl are making out but they don't want to have sex, so the boy pauses to ejaculate into a condom. He then slaps the girl with the condom full of his essence and they laugh and continue making out.
Boy: Whoa hold on a second! (ejaculates into condom)
Girl: Hey, what are you gonna do with that?
Boy: (coslaps her) Haha! You got coslapped!