Mario's EXTRAS: High School Mario is a video uploaded by TheAwesomeMario.
Follow Mario & his friends thrugh their silly lessons in school!
The deleted scenes consist of:
Luigi was reenacting a Shakespeare play, only for Mario to come in as Jesus thinking that he's in a Christmas play. Luigi initially seemed annoyed by that, only for Wario to bust in as a Christmas tree and cause Luigi to rage.
Show and Tell
The Left Shark announced that it's Show and Tell time, although everyone except Fishy Boopkins were unwilling to go in front of the class to present their "object." Eventually Boopkins did show his "object," which happens to be one of his body pillows despite Left Shark's reminder that he'd call the student's parents if he brings it. After introducing the pillow, all the other students started making fun of Boopkins with Bowser calling it "gay," eventually causing the Spike to become upset and leave with it.
Squidward Tentacles convinced the class to repeat after what he did with his clarinet. However, this only caused most of the students to blow into their instruments as if they were wind instruments (with the exception of Bowser, who simply banged his drums in the meantime). Still, despite mostly playing their instruments the wrong way, the gang was still praised and congratulated by Fishy Boopkins for their "music."
Mario was sent to the principal's office for setting one of the "dinner ladies" on fire, even when he claimed that it was an accident. But when he tried to explain what he did, he was silenced by the principal who revealed himself to be Elmo. That caused Mario to laugh, shortly before he got threatened with a RPG from the Sesame Street character.
Mario ended up in detention with Bowser and Wario, presumably as a result of laughing at Elmo and burning the dinner lady. In the detention room, Kermit decided to sing a song called the "Detention Song" to teach the three men to behave, encouraging them to sing along with him. However, none of them sang it despite the "time and effort" that the frog Muppet put into it.