Jack was looking at a nice brunette, when the change begins. starting from the girl's feet. Under Jack's eyes, at the moment they grow several shoe sizes, going from cute and feminine to large and hairy.
The change continue to move upward, as muscles swell in her legs and hair grows over them. In her crotch area, everything looked the same under her bikini bottom, leaving her a woman where it counts, except for the furry hairy mass who poked upward,
Then, the change goes on moving over her stomach. A trail of hair sprouts, originating somewhere beneath the elastic of her bikini bottom and stopping just below her bellybutton. More than the hair, her stomach hardens and tightens into washboard abs, and when the light reaches her chest her breasts shrink and pectoral muscles swell. He sees how hairy her chest is for few moments, but then her bikini top turns into a t-shirt. Jack can still tell how hairy she is, since her heavily muscled arms are also covered in dark hairs.
Lastly the transformation spreads on her face, watching as her black hair shortens into a masculine style and sideburns grow in as well as a five-o-clock shadow.