The act of two males(possibly females) running towards eachother. Upon meeting, they jump in the air, feet first, with their legs spread. Idealy their legs straddle eachothers bodies making it possible for their lower genitalias to collide. As seen on Jackass 3.5
the movie with Bam Margera and Ryan Dunn.
Those guys just did the Flying Nun High Five and totally smashed their balls together.