Cell phones
Seriously, just don't use them at school, unless you're at lunch.
PDA
Basically, everyone tries to stop PDA, but yeah...it doesn't stop a lot of it. Just prepare to see two humans sucking each other's face, and it will disturb you for the rest of your days. Also, if you are one of those people, stop being a jerk bag! We're glad you have a relationship of sorts, but come on! Just get a room. Not a classroom, but your own room that isn't here or any public place.
Homework
If you don't read Larry the Cable Guy's language...Just get your homework finished!
Missing School
There's really not a whole lot of funny things about missing school...don't do it! You're not Ferris Bueller, so don't even try it! If you don't know what Ferris Bueller's Day Off is, then go watch it and enjoy!