To unlock the kissing mechanic, Jimmy must complete his Art 1 class. Every Art class will give Jimmy some sort of a kissing bonus. At this point Jimmy will have the option to kiss any of the girls his own age, as well as one boy per clique in exchange for a gift, although he will not get favorable reactions from students whose clique he is in bad standing with if he tries to hit on them. The girls he can approach are Eunice, Beatrice, Angie, Christy, Pinky, Lola, Mandy and Zoe. He can give them either flowers or chocolates, although Eunice will only take chocolates. Jimmy kisses Eunice and all the clique girls during the game's storyline, and he kisses Angie as part of a tutorial after completing Art 1. He can go through the entire game without kissing Christy.
It is actually possible to kiss clique girls before they officially become Jimmy's girlfriend, even as early as Chapter 1. To do this, Jimmy's faction standing must be 50%, and the kiss must be attempted in an indoor area like the Library or the Girl's Dorm. Whether she will accept or not is a matter of luck, and factors like location and Jimmy's outfit are thought to be involved.
Every time Jimmy completes an Art class, the kiss rewards more of a health bonus, and the kiss becomes more intimate with every Art class completed. After Art 1 is completed it is a light peck, however by the time Art 4 is completed, Jimmy has the ability to do a full make-out with a girl. In the Xbox 360 version of Scholarship Edition, Jimmy will always do a full make-out with the girls. As the kiss level increases so does the health bonus. After passing Art 1 the bonus is 25%, Arts 2, 3, and 4 raise the bonus to 50%, 75% and 100% respectively. After Art 5, Jimmy no longer has to buy the girls a gift to get them to kiss him. Eunice only has one kissing animation, in which she leans clumsily on Jimmy and slobbers on his face, but Jimmy gets all the same bonuses for kissing her that he does with the other girls. Excluding Eunice, all girls have different kissing voices but same poses.
Jimmy can also kiss Mrs. Lisburn after an errand where he helps her escape from the retirement home. At the Freak Show, if the player targets Delilah and Jezebel or Courtney, the kiss icon appears, but since they are inaccessible behind glass he can't actually kiss them. This is likely caused by the fact that they are rigged to "Medium" skeletons, the same skeleton as the female students.
One boy from each clique can be kissed, those being Cornelius, Vance, Trent, Gord, Kirby and Duncan. There is only one animation for this. If Zack Owens is added to free roam via hex editing he can also be kissed. He has the same kissing animation as Eunice.
Once Jimmy has kissed a character, his faction standing with that character will always be 100%, even if he has fallen out with that character's clique. If a character who Jimmy has kissed sees him kissing another character, they will attack either Jimmy or the person he kissed. Girls will either grab each other's hair and pull, or attack either person with a knee to the crotch or a slap, but guys will start a fist fight, either against Jimmy himself or the character he's kissing, even if it's a girl.