They keep making it look like Billy actually ditched but if you listen to the whole song he IS actually at school. He has his GF call his mom pretending to be someone at the school telling her Billy isn't there so his mom will go to the school and see Billy is there as a distraction while his GF who faked sick sneaks into Billy's mom's house to get alcohol, replace the alcohol in the bottles with water and come pick him up after his mom goes to work after the distraction. The plan fails because Billy's mom calls the number that called her back and it goes to Billy's GF's voicemail and Billy's mom quickly unravels the plan and both Billy and his GF end up grounded.
