How do i deal with a smart ass, mouthy 17 yr old boy (son) that thinks he knows everything?

Smart mouth: Assuming he is still in school, getting feedback from teachers, counselors, coworkers, etc is the first step. If others agree that his behavior is distracting and making him non-functional, visit a primary care doc or psychiatrist. There are certainly disorders like anxiety, depression, or even oppositional defiance disorder that may be precipitating this behavior. Good luck!

Know your limits: This is an issue that likely requires some help. Teens enter a period similar to the terrible twos, and some can deal with it and some not. I would encourage you to visit a family counselor, together and/or separately.An evaluation of the situation could identify an emerging emotional problem in the teen and help you both develop some coping skills to get through this period.