"I'm going to need both of you to strip down into this in order to run the experiment" said the doctor, handing the boys a long shirt that went down to their knees but didn't cover their back. "Matt, your bed is on the left and Jason, your bed is on the right. A nurse will be with you boys in a minute. Any questions?". "Yeah", said Jason, "how long's this gonna be? I don't wanna miss my shows." "I told you Jason, just an hour today and we'll come back tomorrow, listen to me for once!" Matt said agitated.
The doctor left the room after explaining the procedure, leaving Matt and Jason to wait for the nurse to arrive. The brothers agree to look the other way while changing, but they both can't help it and look at each other. Matt saw Jason had quite a long visible outline in his underwear "Damn Jason, when did you get a snake in your pants?" Jason responded surprised "Wha? It's not as big as yours". Looking at the thick bulge in Matts underwear. Matt thought that Jason's was longer than his at that age and quite on his way to his length. Matt himself was very impressively endowed his flaccid being 7 inch and very thick. Jason's in comparison was a long slim wiener but he seemed to be a little over 5 inch long flaccid himself very impressive non-the-less.
They were interrupted by the nurse, who told them to lay on the bed and lay out their arms while she was scribbling down something on a notepad. Two injections later and a reminder to come back tomorrow and the boys were send off. Back home the two of them get surprisingly hungry eating a couple of things they normally didn't like. They then quickly became tired and went to bed. While they were sleeping changes were occurring. Matt's member inflated slowly, his shaft bulging out and while becoming a bit longer gaining more and more girth while it's length slowly increased. Jason was undergoing changes of his own, his shaft started lengthening more and more while his girth barely increased.