[ignoring, here, that Zoe would actually remember Karyn as always having been big-chested and blonde, because continuity is over-rated :]
Zoe concentrated, "I wish that Karyn's breasts were two cup sizes larger than they appear to be, and that she always dressed to show as much cleavage as possible, and that her hair would always be her natural color." No more dye jobs for you, thought Zoe.
Jon's eyes bugged out as Karyn's already-large chest expanded to gargantuan proportions, and as her shirt changed to a very low-cut tank top. Zoe was disappointed, however, in that her hair color did not change, and that there was no sign of the bra having been stuffed, previously.
Karyn's reaction was much more direct, though. "What are you doing? The weight of my chest was killing me before. Now it's twice as bad!"