Why can girls wear bogs clothes but boys always get made fun of when they wear girls clothes? ?

I saw a women in the mall and she was wearing a mend t shirt of the ironman and you could tell and then when I kept walking I saw some freshmen boys and girls picking in an other freshmen that was stuck in the corner wearing nothing but a pair of panties and a bra the bra was blue with stars and he was wearing pink hello kitty panties I sat watched this go down