Your cock was pulsing hard between your legs, and you knew this was mostly because of your girlfriend's arousal, she really wanted to try your cock. Before you could do anything, your girlfriend's cell phone rang and she answered it, but not before telling you to fondle your shared cock while she talked.
"I'm glad you answered Gabby (as they used to call your girlfriend, whose name was Gabrielle). We need your urgent help." said Cyntia, one of her friends
"And it has to be in person, you have to come here now." Said the voice of Rose, who was next to Cynthia.
"I'm sorry, but we can't leave right now." you, who could hear what they were saying, said it, but as your voice was now the same as your girlfriend's, her friends thought that it was she who said it.
"That's right, we're a little too busy to hang out right now. But if you want to come here you are welcome." your girlfriend said
"Please, come. There's no way we can get out of here, at least the way we are now." Rose said
"We are serious. That witch found us and cursed us, and she said only you can break the curse." Cynthia said
"Right. I'm just going to finish something quick and I'll run over there real quick." your girlfriend
Your girlfriend's friends hung up shortly after thanking you, so you sped up your pace in jerking off, thus cumming relatively quickly. You then dressed quickly in one of her clothes and left. The chosen option was the only one that was comfortable was a blue dress, because even her clothes still fit, this was the only one with comfortable space for a version of her with two heads. You also left without any underwear, because her panties all hurt due to the presence of your dick there and your male underwear was too loose on her, falling all the time. As you expected, you caught the attention of people who saw you on the way, but you tried your best to ignore them.
Arriving at the indicated place, which was Rose's house, they found a note by the door saying that the back entrance was unlocked, so you entered through there. You went up to Rose's room, where some moans came from, and upon entering, you saw that the curse cast on them would not allow them to go out in public at all. You saw two girls hugging each other, neither of which had a head, but a pussy lodged between their shoulders. Both girls had a 9 or 10 inch cock between their legs, and each had their mouth on the tip of their cock, which were touching as they kissed.
You and your girlfriend were able to differentiate which was Cynthia and which was Rose by the nail polish they wore and by their skin tone, which Cynthia's was slightly darker.
You watched the cursed girls hugging and kissing each other until they pointed up and came, with a huge amount of cum coming out of their big ballsacks (which you only noticed at this point) and spurting out of their mouths.
"Sorry to make you see that Gabby, but the witch's curse has turned us into these shapes and has us constantly aroused. It's hard to resist and once we start we can't stop." Rose said, now with both girls looking at you, letting you see that not only did they have their mouths on the tip of their cocks, but that their eyes were on their balls.
"Why do you have two heads now Gabby? Is it because of the curse that hit you?" Cynthia asked
You and your girlfriend told your side of events, then Cynrhia and Rose told their side of how the witch found them and cursed them for showing no remorse after their girlfriend was cursed in their place. The pair also explained that, according to the witch, they would be excited all the time and trapped in that form, but that they would go back to normal if your girlfriend made them come.