How did I gain a six pack over night?

I'm not making this up and Iv only just noticed this today. Well first off I do practically nothing all the time and yesterday I did not have a six pack little known the outline of one. But then today I looked in the mirror and noticed literally all my muscles my arms, legs, back and abdominal are suddenly all more enhanced. I could literally see a huge difference from yesterday, I did no exercise apart from like a few push ups but that is not enough to enhance ALL my muscles! Any possible ideas?
How did I gain a six pack over night?
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