v. An event where the male's genitalia becomes stimulated to the point that the testicles ("balls") appear to sneeze, ejaculating semen from the male's penis in the way snot would be ejaculated from his nose in an actual sneeze. Typically happens during sexual intercourse or foreplay, but may happen prematurely as well.
Aw fuck, man! Look at all that ballsneeze on the sheets! What are you god damn doing? Clean up that fucking mess!