When the booty is too thick to slap so you need to take a great amount of force to the booty. this would cause a rippling affect which would make the female (or male) moan. Sometimes it can be used by hand or by genitals.
"That ass was so thicc, I had to use the Smacc Attacc"
You motherfucker. You think you can define Zach Attack? That hard ass motherfucker will fuck your shit into the fourteenth dimension and back. How about this. He bites into a dorito loco taco and the eighty four women closest to him orgasm so hard their vaginas start vibrating. At this point, the dopamines literally start leaking out of their ears, nose and mouth, sometimes causing asphyxiation and/or divorce.
Fred: Oh god, i just read the description of Zach Attack on Urban dictionary!
Velma: yeah, thank heavens he does not like mexican food.