In case you're ever in a group musical class-type situation, with one teacher and many instruments, here's some advice from my fellow guitar classmates:
Make sure you don't practice anything during the week. That way you can learn lots during class time.
When the teacher asks for a volunteer to play something, do anything but raise your hand. Instead, pick your nose, text your friends, or play your instrument quietly to yourself for twenty minutes while no one else raises their hand.
If by some mysterious chance, somebody volunteers to play, don't listen to them. Don't pretend to listen to them, either, and definately don't let anyone else listen. Play loudly over them to make sure a healthy cacophony is maintained in the classroom. This way everyone remains equal in your eyes and those of the teacher.
I'm not sure if you understood that last one, and it's important and bears repeating. If it looks like the teacher may be listening in concentration to a fellow-student's playing, stand up and play with all your might. But play a completely different genre than the class is for. Preferably an overplayed radio song. This will make you rise in your teacher's esteem for your guitarry prowess.