x.
He tells her why there is no way in hell he is going on stage in front of the whole school in his tighty-whities. And the fact that she understands immediately- that right away she understands his insecurities- makes him feel guilty. Because he knows that she, too, has some, though they remain hidden. And he knows that her fears about fitting in- her insane need to be accepted- comes from the teasing and bullying that she endures every day. Which only makes him feel worse, because he used to do that to her.
He makes a promise to himself that no matter what, he will make up for all the pain he caused her.
Little does he know that the three little words that he first uttered at Regionals already did.