She really wanted to see if she could make the change last without having the shirt on. There was an extremely exciting nature to the thought of being with three breasts and having them unobstructed. She would enjoy it. Her boyfriend would probably enjoy it too. But, she did not know the nature of these shirts' magic. Would cutting the shirt stop them from working? Or worse, would it leave her with whatever transformation it bestowed with no way of reversing it.
She loved having three breasts, but always having them would be a problem. So, after a moment of rubbing her hand along her third breast, she pulled the shirt off. As expected, once it had come over her head and she could see herself, her torso had returned to its usual, two-breasted self.
She put the purple shirt back down on the bed and looked across the rest of them. To test this, she needed to find something covert, something she would not mind being stuck with if it became permanent, but also something she would not miss if it simply stopped working. Though of course, she had no idea which met that criteria. The effects of all the shirts were a mystery. So, for now, she would have to continue experimenting.
Returning to the shirts laid on her bed...