Occurs after a night of drinking. When you're not quite hungover -no vomiting, headache, or promises never to drink again- but you don't feel like yourself.

Often characterized by silly mistakes, dropping things, slight physical discomfort and lethargy.

Analogous to a car making funny noises. It starts and drives, but it's just not running right.
"I've been puking all morning! Man, I'm never drinking vodka again... How are you feeling?"

"Not too bad, just a little 'Spark Knock'"
by Chloe May 22, 2006
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