When a very hot girl with a very,very short skirt kicks or knees a male in his testicles,more commonly known as balls.
An example of a Mini-Skirt BallBust is when a very hot girl with a short skirt pretends like she wants to kiss you. She puts your arms on your shoulders and brings her lips closer. Just when she is abot to kiss you, she knees you square in the balls, and you go down.
Person 1: Hey man! that chick is so hot!
Person 2: nahhh, did you see her up close? you just fell for the Mini Skirt Effect!
Person 1: oh yeah! youre totally right!