Ty connect Dustin punishment. Ty decided that anyone that picked on another person that picks on another will suffer a similar fate.
So while Milo was picking on Dustin he had started to get punished also but instead becoming younger he would either lose or gain maleness. For each time he picks on someone younger or handicapped he will lose 5% of his maleness and every time he does something to help will give him back 2% of maleness and that if he reaches no maleness left that he will then start to have his male personality to change also at the same rate.
Ty then went on his way when Milo had picked on a kid in 2nd grade. So Milo had lost 10% of his maleness.