Jon was tired of being what (in his own mind at least) was one of the last virgins in his school, so he knew exactly what wish he would make.
"I wish that before the end of the day I will have sex, that it would feel great, and it would be with the perfect partner for pleasuring me."
Little did Jon know this was the mammary stone, it could grow breasts on you anywhere, any size, and number, any type. In a way he lucked out, he didn't grow roasted chicken breasts, on the other side what did happen would make his wish awkward.
Jons genitals felt funny. His balls felt like they were swelling but his dick felt like it was shrinking. Jon looked down at the huge round bulge between his legs and lifted his underwear to peek inside. he was shocked to see a large breast between his legs instead of his genitals. he took a few steps to the mirror to get a better look and it felt odd, his legs kept rubbing against the large soft mound while his breast jiggled with every step. The jnipple rubbing against the fabric of his briefs felt good and was making it grow hard.