My rottie pup b has nipped me in total of 3 times. This is because on the 1st time she nipped me,I said NO! And put my hand in her mouth, grabbed her bottom jaw and pressed against the bottom jaw bit with my hand, it doesn't hurt them, it just tires them.. The 2nd time, I said NO! And folded my arms, turning my back to her, the third time I did exactly the same, that was 4months ago now, and she's 7 months.. She hasn't nipped anyone since, now she just paws for your attention!!