When I brush, I keep brushing until I am fairly confident that I cleaned everything, usually about 4-5 minutes. This includes areas like the sides of your molars, the top of your teeth, and the tongue, not just front and back of your teeth.
Not everyone in your life is automatically a friend. Not everyone you talk to is your friend. Some are just classmates, coworkers, acquaintances, or people you happen to spend time with.