The guys grope her tits.

The boys start to play with her tits, the rub her nipples to make them hard, Katie is thrashing but she can do nothing while they hold her in place. She starts to cry when a boy start to suck her hard little nipple, while the other one rubs up and down her nipple fast. She will admit it felt good, but not good enough to over power her humiliation she was feeling. Eventually the boys got bored and let her go. But not before securing her to the seat with tape from their bags. Making sure she sat with her ass out in the walk way for everyone to slap, grope and see. She started crying by that point again, after everyone on the bus left, her ass must have been red from all the smacking, the bus driver didn't even attemp to help, and she missed her first day of school. But eventually broke free and got off at her stop and ran to her house. There she had a shower and went straight to sleep, still naked, and still scarred and humiliated.