skull splitter

noun2

1. •
   A severe headache or migraine.

   • If you're lucky you'll get nauseous and sleepy and develop a skull-splitter of a headache. if you're not, the thing will simply explode. — 2004
2. •
   (slang) Any highly potent alcoholic beverage, mixed drink, or knock-off spirit designed to give the drinker a severe hangover.

   • You don't want that at this time of day; that's a skull splitter. — 1985