Unable to think clearly with all the excitement she felt at the moment, Penny didn't even question herself, she just wanted to try out her new dicks. She ran behind Tony and Becca and positioned herself to fuck their shared asshole. Tony tried to free himself, but couldn't because Becca wanted to be fucked and he didn't have full control over their body.
Penny pushed her cock, which stretched and entered Tony and Becca's asshole, with the shape of her member visible in the bulge on their belly with each thrust.
The impact of the two pairs of huge balls generated loud sounds, which attracted the walking cock Jane, who bent down and inserted herself into Penny's ass, who now only produced nasal sounds since she no longer had a mouth. Jane began to lead the rhythm of the thrusts, with Penny hugging Tony and Becca from behind, with her dickarms passing under their arms and placing her head between their heads, trying to encourage one of them to suck the cock on her face. Becca did so and Penny stroked their shared dick with her dickarms.
It happened like a chain reaction, Jane came inside Penny, making her cum inside Tony/Becca, who also came soon after. What they didn't know was that one of Jane's new mutations altered the chemistry of her cum, making it have the same effect as the pills on people.
With the new contamination, as they recovered from the orgasm, Tony/Becca's cock grew enormously, reaching a total length of 5 feet. Their sack merged with Penny's so that their four testicles shared space in the same ballsack, their entire body (with the exception of their heads) grew while Penny completely merged with them, her breasts and dickarms lying beneath the couple's originals as her head found its new resting place between theirs.
During the new transformation, Jane went out of the bathroom and they didn't know where she went to. The trio that now shared a single body stood up, now almost eight feet tall, and went looking for Jane.