1. slang An intensely painful headache or migraine. It started as just a twinge of pain in my forehead, but by the end of the day I was in the throes a full-blown skull-popper. It was a great night, but I woke up with a real skull-popper and the worst nausea of my life.
2. slang Something very confusing, complicated, or puzzling. A: "There just doesn't seem to be a way we can reach our quotas without going over budget." B: "It's a skull-popper, to be sure." I love trying to figure out the crosswords in the newspaper each Sunday. Today's is a total skull-popper!
3. slang Something that stimulates one's senses to an extreme degree. Wow, this beer you gave me is a real skull-popper! What's the alcohol per volume on that stuff?