You and him have become enemies with certain things on the campus.

At that, you accidentally passed a music class and heard someone playing musical instruments and even singing in that room, you also peek and see your enemy is playing a electric guitar and then he sings a song: (Bad Romance -Lady Gaga)

A few moments later he had finished playing his guitar and saw you peeking in the window

"Like someone was peeking at me while playing guitar."

He said, with smirk on his face