"Ball busting" is the practice of kicking or kneeing men in the testicles. It carries several medical risks, including the danger of testicular rupture from blunt trauma.
I was fucking a girl and I wanted to surprise her afterwards, so I squeezed my dick between her ass cheeks and took a picture. She said it sorta looked like a hot-dog. Hot-dog bunning has become a running gag in our house now.