"Balls Across the Nose" is an act of sexual humiliation similar to teabagging, where a male will drape his testicles across the bridge of another person's nose. The "victim" is often inebriated, unconscious, or in an otherwise compromising position.
I was scared that if I dipped my nuts in Tim's mouth that he'd clamp down on them like a fox in a leg trap. So, I took the safe root and just went Balls Across the Nose. Don't worry, it was just as funny - and we got pictures.