This is a truly humiliating attack one can do to a boy. It involves the simple act of hitting them in the balls, usually with a quick flick motion. When he is doubled over in pain it is followed by a painful slap on the ass. It’s a spanking they won’t forget and whoever does it is a badass.
Example 1
Jake: Why is everyone laughing at robin?
Tanner: Jordan attacked him. It was a sac tap butt slap
Jake: Damn!
Example 2
Brent was standing around minding his own business when Robin and Derek got him with a sac tap butt slap. Robin hit him in the balls, Derek slapped his ass. It was embarrassing for Brent.