"Seems like a good opportunity for a summer themed caption! Maybe a girl coaxes her boyfriend into trying on a pretty one-piece swimsuit for her and it slowly transforms him into a girl as well? If you'd like, the rate of feminization could increase along with his embarrassment until he's just forced to accept that's he a girl now."

---Text:

Quite an old story for this kind of tale, boy loves girl... but girl only loves girls.

Lucky for Sam he got his girlfriend non-girlfriend to give him an out.

“Come with me to the beach wearing this and you can stay with me.”

“But... but I can’t wear this in public... it’s for girls...!”

“So? Prove that you are a manly man and if not... well...” she smirked. “Up to you if you follow me...!”

The girl left, the guy didn’t think twice about it, he undressed and put on the girly one piece swimsuit and ran after her.

As soon as he was outside he gulped and blushed, it was embarrassing, ridiculous, the tiny piece of cloth stretched over his body, over his thing... but the girl was there and he followed her...

The shame was crushing, more and more eyes looked back at him... he felt a warm tingle all over his body... the smothering of his skin... the widening of the hips...

An inflation in his chest, his thing flaccid, shrinking, and yet so, so hot...

They hadn’t even reached the shore when the girl looked back, still smirking... the blushing girl stopped, still slightly red... the swimsuit fitting perfectly...

“Everything fine, darling?” asked the first girl.

Her nipples rubbing the inner fabric of the suit, that gentle warm wrapping around her crotch...

Sam nodded as softly as she could and answered with an even softer voice.

“...Yes…” she mumbled. “Yes... everything is alright...”