Definition of "skulling"

Maybe he would die. That would mean I had murdered him. I smiled, trying the idea on for size. One of the things that always had cheesed me a little was that I had no kills to my credit. I'd been in plenty of rumbles, but somehow, I'd never cooled anyone. Well maybe now I had my first one. I couldn't feel very proud of skulling an old man, but at least I could say that I'd scored. That was a big kick.

1965, Sex Jungle (narrated in Perversion for Profit)