I find it quite funny how many players want the "Christine party event" cut out! This is actually one of the few side event chains with potential for the overall storyline!
It could be a path where Dylan leaves his mom´s orbit for good, because he finds a girlfriend his age.
-Christine is a bit of a wild child, but it is established early on in the game that she has a soft spot for Dylan. (even if Ellie does not want to see it at that time)
-Christine is a very open girl, regularly showering with her Mom and going by the fact that she mostly gets away with her shenigans, it is likely she visits her Dads shower somewhat regular too.
-if the player pursues Christine, she is mentioned to be the reason why Dylan wants to "experiment" with his Mom.
-if you are on the route where Dylan and Ellie reconcil, Christine and her friends accepting Dylan surely helps
This sleep over party can be leading to Dylan-Christine and/or Dylan-Ellie, maybe even a threesome Dylan/Christine/Ellie. Depending on the games played and wagers done, it could even be a hilarious variant, say Christine becomes Dylan´s girlfriend, but he has to become a member of the cheerleader squad also.
While that would be a hard thing for Dylan, given what we heard earlier in the game, it would be sweetened by the fact that the head cheerleader would be his girlfriend. So screw the crude jokes of the others.
This party has quite some story potential.