A well-placed and extremely hard blow to the testicles. Done correctly, a nutbuster will incapacitate even the strongest man for several minutes. Best results are usually achieved with a kick, using the laces of any sturdy shoe. Other methods of nutbuster delivery include a baseball on the end of a rope, knees, or even a strong punch.
She gave me a nutbuster and I was writing in pain on the floor for 10 minutes.