when a female passes gas on to a males testicles and scrotum during intense and deep sex, most notable in the missionary position.
"doooood I was slayin this broad sooooooo hard last night that she totally ballfarted me. you know if she don't ballfart, you aint doin it right, kid."
"oh lover when you ballfart me, it is as if a pleasent zephyr passes over my testicular hairs, like a gust through a meadow of sugarcane"
When you squeeze your asscheeks together while farting, the air is focred downward and through the side of your balls. Awesome noise.
Hey dude, you wanna have a Ball Fart contest?