"Lets keep the fun going" replied Bobby. "Both."
Emma smiled. "Join us in the pool."
Bobby slipped into the pool, feeling water on his transformed waist area for the first time. He expected to feel more in his legs as he became a merman with a dolphin tail. Except he didn't. He didn't feel his legs changing because they weren't. He surfaced next to the two dolphin-tailed mermaids who had resumed making out.
"I've still got legs" he announced.
They stopped kissing and looked at him. "That's weird" said Jenn. "No changes at all?"
"Only the ones I picked up from Emma earlier."
Jenn looked at Emma and they both understood. Jenn swam over to Bobby. "I noticed how you look at me" she said. They kissed and Bobby could feel himself unsheath. Emma swap up behind Jenn and began kissing her neck and folding her breasts as Bobby slid in. He wrapped his legs around both of the dolphin girls' tails and began to thrust. Jenn moaned with pleasure as she was sandwiched, but Bobby soon realized something was wrong.
"I'm stuck" he said. "I can't pull out."
"Oh shit, so am I" said Emma. She couldn't remove her hands from Jenn's breasts.
The three tried move their tails and legs, but they seemed glued together.
"What the hell is going on?" screamed Emma.
"It must be the Transform or Dare curse" said Jenn. "Bobby has joined us - not as a mer dolphin like you intended, but literally!"