He Doesn't have to do anything

Zach realized that doing something as bold as that would not be a good idea. But as he was thinking this he Groaned as Hannah pushed her ass into his groin, smashing his hard shaft between her ass cheeks.
Zach couldn't believe this was happening, his childhood crush was grinding her amazing ass on him making him harder and harder. She looked back at him and bit her lip. "Don't worry, its all part of the stretch." She said. He nodded and continued to indure Hannah moving her ass up and down, stoking his shaft with her ass.
"Aren't you suppose to do these kinds of stretches naked?" Zach said and immediately wished he didn't.
Hannah looked at him and said: