The Jim Paradox continues into Season 4 with analysis for every episode on a scene-by-scene basis, (episodes will be uploaded by title as individual chapters). Analysis focuses on Jim’s character development on emotional and psychological levels with emphasis on how his behavior impacts JAM. Also included are the QTPs (Question to Ponder) that incited so much discussion on the message boards. 

A drunken phone call between Pam and Jim, set in Season 3. 

Warning: References to alcohol

DISCLAIMER:  I don't own the Office.  If I did, there would be more drunk Pam. 

People always assume that Pam Beesly is as sweet in the bedroom as she is an all other realms of her life. A missionary-only type of girl, the girl you treat like glass.

Little do they know, she just wants Jim to shatter her, break her into little pieces. She decides she's done waiting for what she wants.

It's always the quiet ones.

Pam thinks of Jim.

Set somewhere in the midst of Season 2. 

So. There is an entire deleted B-Roll from "Sex Ed" where Pam and Jim are fighting all day, and then he slaps her butt on the way out. It's never explained. This is my explanation.