Quiz time

My friend sent me an email talking about one of her students. This is what she wrote...

"Is very big. He is always playing and twisting it in lessons and I always wondered if it was hard. So I touched it and the first time I think he was a bit shocked (as I was standing behind him talking to his friend) [....] but then after I'd helped someone else his friend said I could touch it again so I did. It was hard."

What is she talking about? Guesses in the comments sections please...