>>2527884You have to wait until a lotion event or pool hopping event comes around again.
Essentially how it works is that you buy these special lotions at the event shop that change the parameters of boobs and butts. You can change how much jiggle and how much sag they've got, though the sag isnt done very well imo so I rarely touch that shape stat.
The skill you get is determined by what the girl is wearing during the event. If she's wearing a fully awakened SR from that event you'll get an SSR STM 7 skill. If she's wearing the trendy for that week you'll get a much better SSR POW skill instead.
You get these skills by gifting the girls boob bounce lotions and you can lock the bounce level if you want to get the skills without increasing the bounce. And if you'd like to remove the lotion skills there are cleansing milk items. You cant pick what skills to remove however. The milk will clean every skill on the girl. The bounce levels will go too if you dont lock them beforehand.
There's also a separate system during pool hopping where you can win EX lotions. If you get lucky you'll land on a space that rewards a single ex lotion (POW, TEC, STM) that grants an EX SSR skill. EX lotion skills also cant be wiped away with regular cleansing milk. They'll be stuck on the girl until you use a special cleaner.