A similar conversation in 1998 would have gone a little differently.
Shawn: "You and those damn acronyms... can't you just say 'ha ha that is funny?'"
(it took "lol" and "wtf" a while to become common use, too)
I guess her thought-out-plan is blackmailing her mother.
The question is, if she's out celebrating, where's Joey? Sitting at home alone while he reads happy birthday texts from people who are partying without him? Diff'rent strokes, I guess.