You weren't sure where you found it exactly, but you ended up finding some sort of toy gun with "Impregnator" written on one side and a dial on the other with a bunch of numbers on it currently set to 1, and there seemed to be two triggers next to each other. One directly below the first one so close they seemed like one trigger at first.
This thing looked like a toy so you fired the gun at your reflection and it fired a small lazer which reflected off the mirror and hit you. You watched as your body shifted and grew smaller and more curvy. Two bulges formed on your chest as the bulge at your crotch shrank to nothingness. Surprised you pulled the trigger a second time and then as you were hit your belly started to swell a little bit and your breasts were feeling a little tender. The impregnator had turned you into a pregnant woman. Curious you tried the second trigger and watched as your belly bulge shrunk back and your boobs reverted. Thinking it would help you pressed the second trigger again and you were sure you weren't pregnant anymore, but your body was still female. No matter how much you mashed the trigger you were still a girl. You went in a bit of a panic as it's not like the "toy" gun had changed anything other than your body. you were still wearing your guy clothes and your shirt was irritating your nipples a bit. Going fuck it you just took off your top and look at your boobs which filled your hands nicely.
Feeling thirsty you had an odd idea and shot yourself with the impregnator and watched your belly grow a bit, and fired again, and again watching as you were in the third trimester and your breasts were engorged with milk. Your boobs reached your mouth and you tried suckling on them. The milk was warm and nice, and the sensation of suckling was kind of interesting. Feeling satisfied you then aborted whatever was growing in you if anything was and your breasts shrank back to their "normal" size.
You thought to yourself "What am I going to do? Do I dare move the dial? What are my friends and family going to say? The heck am I going to do?!?"