As Drew pulled the trigger he felt weird in his nether regions, and wanted to investigate it he ran to the bathroom to take a look at his privates. Sue thought to herself "That was odd... just like.. my crotch?" with no one else around she pulled her pajama pants out and checked her groin and saw a little boy's penis growing there. Sue then thought "Ok, so did Drew get my pussy? Wait didn't the vagina give off estrogen and the penis give off testosterone?" She was right to be concerned but the penis hadn't gone through puberty yet and was only giving off small amounts of testosterone, but not enough to really change her. Sue sighed and said "I'm going to get that gun back."
Meanwhile Drew in the bathroom was discovering what a developed pussy was like to have. He poked it a bit and found out the pleasure he got from it, but that's not the only thing he found. The gun's change made his vagina output a lot more estrogen during the development of the vagina. As a result Drew's chest actually grew into A-cups on the border of B-cups and wider hips/butt. S/he locked the door and tried to think how he would get out of his now feminine body.