Zeus was bored. Really bored. There was nothing for him to do but sit around and listen Poseidon and Athena argue. He really didn't want to do that.
He walked out of the throne room and decided to to practice his flute. That's right, the powerful and almighty Zeus plays the flute. Actually, he plays a lot of instruments. He can master each one in an hour.
Anyway, while Zeus was putting together his flute, Apollo snuck in to watch Zeus play.
Let's just say it didn't end well for Apollo.