Get a part-time teaching job. By the time you're frustrated, you're done. This helps enormously.
Agree with everything the disrespectful students say:
Student: I wish we had our old teacher back!
Me: I know, it's awful that you're stuck with me now.
Student: You're so mean!
Me: I really am! People tell me that a lot.
Student: You're the meanest teacher ever!
Me: Pretty much, yes.
Student: I'm going to get you fired!
Me: You should definitely tell the principal to fire me because I'm making you work.
Oh, this is way too much fun.