enter nebbys shop but dont click on anything yet look on the botton you will see an tiny arrow and pressing it will show the tab "outfits" and click it then buy the flattering bikini for 1000g i think then go to the lake and interact and use the strange pill for 2nd round scene
Tap buy then look in the bottom youll see an tiny arrow then youll see the outfit tab and tap it and buy the flattering bikini if im wrong ill send pictures on how to do it
Buy Flattering Bikini in Nebby's shop, the option should be at the very bottom, then go to the lake at the right side of the map. The rest should be easy.