That was... expected.

He was cute, with a wonderfully pert ass.  And some gorgeous legs.  So therefore it was really no surprise that it happened at all.

It's a natural reaction.  It happens when the nervous system activates a rapid increase in blood flow. The vascular muscle in the spongy area becomes engorged with blood and the outflow of blood is cut off.  

Translation: I popped wood while adjusting a cute guy during class.  

This isn't the first time something like this has happened, but this was the first time something like this took place during my naked class.  

I had placed my hand on his left hip, keeping it stable as I stretched his right leg.  That's when his penis fell onto my hand.  I looked at his face, trying to determine if I should shake it off, cuz my hand was where it needed to be for the adjustment.  As I looked at his face, his eyes closed, an expression showing he was focusing only on the stretch, I felt the stir.  I looked at my own crotch and noticed that it was coming to life.

"Crap...  uh... well...  it'll go away before he looks up..."

I cued the transition to the next pose, and as he began to move into it, he lifted his head and looked directly at my erection.

I looked him in the eye as I began to move away, everyone else oblivious in their own poses.  He looked again at my erection, a hint of a smile on his face, and laid down.