2: Some girls feel awkward when you say "pussy" in front of them, thus this term has been created to give "pussy" a funner, more relaxed, and chiller connotation. Fun girls tend to get horny upon hearing the word.
3: Not just any pussy, a pussy that you really want to be in (Thus, the term can even be used to describe the girl as a whole).
(In this context, you shouldn't have to define it for the other person. The other person should immediately be like, "Wizzy?! That's a sick word. You come up with it?"
2: "Girl, lemme get in ya wizzy." (Be slick with this one, let her realize you're a badass)
3: "Brah, let's go fish for some wizzy."
This technique is closely connected to the "shotgun".
Person2: Alright lets do it
Person2:*Snort* Holy shit I'm fucked up from the head rush