1. To hit someone very hard with one's head; to head-butt someone. Primarily heard in UK. He was talking so much nonsense that I felt like grabbing him by the lapels and nutting him!
2. slang To strike someone in the testicles, especially with one's knee. I can't believe Sarah nutted Jake when she found out he had been cheating on her!
See also: nut
1. n. an odd or strange person; a crazy person. Some nut is going to try to fly from the top of one building to another.
2. n. [one’s] head. The baseball came in fast. Clonk! Right on the nut!
3. n. an enthusiast (about something). Paul is a nut about chocolate cake.