"What the heck!" Maria yells to her sister as she sprays her chest.
The transformation started immediately. The gorgeous tits that her sister had flattened quickly, as her entire torso expanded, gaining male muscles and hairiness. Maria was still looking at her little sister while felt a tingle in her chest. She saw in horror that her tits was not only gone, but replaced by a perfect and nice masculine chest, hairier and bigger than that of her boyfriend!
"What have you made..." Maria shouted at Erika, who answered spraying again, this time against her sister's face.
The change was quicker and more interesting. Her jaw line became more and more pronounced and her eyebrows started getting thicker and thicker, heavier too. Her girly feminine softness gave way to sharper lines and features. She was becoming more masculine looking by the second. Stubble grew over all her now decidedly manly face.. a beard, indeed, thick and long 1 inch and at the same color of her hair, who has shortened in a perfect crew cut.
"... to me!??" Completed Maria in a new baritone voice.
"OH MY!" She stopped, touching her beard horrified.
"Change me back!" Maria ordered in her new male voice at her sister.
"I.. I don't know how.." -Erika responded- "That spray seems to transform girls into men, but don't know if that's permanent.. sorry sis.. we'll find a way."