A nutslapper
When you're getting head and your girl starts smacking your nuts like they're a punching bag and you're the dummy in the middle.
My girl was giving me head and then she started hitting my nuts like I was a punching bag.
Getting head was fine until my girl started punching my nuts like I had a grudge against her.
She gave me head and then she went full-on nut slapper like I was her new favorite toy.