The mermaids began to strip your clothing away. Exposing your breasts and body. You try to cover your boobs but the don't seem to bothered by them. One Mermaid begins plating with your breasts, squishing then between her hands. She has one boob in each hand when you notice something strange. Your boos appear to be shrinking.
"What!" You gasp. The pull you closer, rubbing their bodies over you and singing. You feel yourself growing taller and more muscular. Your boobs completely dissappear into strong pectoral muscles. You realize that your body, besides your face and vagina resembles that of a male swmmer.
A mermaid grabs your face and begins to kiss you passionately while rubbing her crotch against yours. Despite your fear you begin to feel around by her touch.
Your face begins shifting beneath her touch becoming more masculine, a strong jaw pushes out and her respond to her kiss. She pulls away and winks and suddenly you are left alone in the middle of the lagoon. You reach your hand down to your crotch and felt your genitals. They are slowly changing beneath your hands. There is a tugging sensation in your crotch as a lump begins to form where your clitoris was. You feel it continue to swell out into your hand and become an odd looking penis. Is is long and vaugly sea green colored. You frown at you sudden change and wonder why the penis doesn't look human.
The answer to your question comes as webbing begins growing between your fingers and gills open up between your ribs.
You are convinced this is some sort of fever dream somehow but everything feels so real.
Your legs start to merge together. A slit forming around your new penis, hiding it and leaving you with a perfectly smooth crotch.
A thin membrane forms between your toes and they stretch out into fins. Your legs continue to grow together, the flesh looking like something out of a horor movies as it grows scales. Your legs grow longer than they previously were while your tail shifts, losing its human joints and becoming much more flexible.
Long fins grow along your arms, and a new dorsal fin sprouts down your back.
Your have kept your long hair but there is no doubt about it. You are now a man, a merman to be exact.