Derived from the SA in the name of welsh beer 'Brains SA.' The reason being after a few pints of brains the resulting hangover will be so bad you will feel as if you're skull is under attack.
Rhys: 'I feel like a pig shat in my head'

Huw: 'Skull Attack was it last night boyo!'
by Lord Manhammer January 13, 2009
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