Fluttershy is usually very hesitant to go to the beach. Not only because of her inherent shyness, but because her skin burns very easily. To accommodate this, Twilight has developed a suntan lotion than can 'absorb the sun's radiation.' This triggers a strange side effect, but Fluttershy quickly learns to live with her new condition. And the massive libido that comes with it.

Fairly standard growth story, which was part of a group-write I did with my Discord group.

Fetishes: Macro, Massive Growth and Masturbation.