The first step to handling disruptive students is making sure you deal with it swiftly. Letting the problem persist without addressing it can make the problem spiral out of control. This may mean immediately addressing the student, or removing them from the classroom altogether -- if the behavior is overly rude. You can send the student to a teacher's assistant or to the principal's office -- until you can deal with him further.
You must keep a strong, firm demeanor when dealing with disruptive students. This lets that student know that you are the boss: It also serves as a reminder to other pupils that you still have control. Speak firmly, in a no nonsense voice, as you tell the student to stop his disruptive behavior. Also, follow through with any consequences you have laid forth.
When you have a moment, collect the student from the principal's office or teacher's assistant, and communicate clearly with him. Explain why he was sent out and exactly what behavior will and will not be tolerated. Let the student know the consequences if the behavior persists, whether it be a call to his parents or a suspension from class.
Once you have dealt with the disruptive student, you may need to address the class as a whole. If the behavior was particularly offensive or rude, ask the students if they have any questions or concerns. If the behavior was minimal and not worth discussing, proceed with your lesson, so you do not reinforce bad behavior.