Like many popular memes, I assumed this already had an entry here, but apparently not. "Post-nut clarity" is online slang for the refractory period after a male orgasms (or "nuts") in which the mind is blissful and able to think clearly (often reflecting in disgust/regret at what you were masturbating to or who you were fucking).
From what I've seen, this is mostly popular on Twitter. The oldest 3 tweets with the phrase were posted successively by @APthe___ on May 9, 2012:
you have to master the art of always having you mind in the state of "post nut clarity"
if you can constantly think w/ "post nut clarity", your powers are truly limitless.
do women experience "post nut clarity" the same way men do?
The earliest mention I found outside Twitter is this forum thread on The Coli from December 17, 2013 titled "Brehs, How Long Does Your Post-Nut Clarity Last? (No Homo)".
Urban Dictionary has 9 definitions of the term, the earliest being from July 4, 2017
On Google Trends, the phrase began bubbling up in the mid 2010's before starting to spike in 2019 and generally increasing to the present day. Most semi-viral tweets I've seen were from 2018 and after.
On March 14, 2019, a clip from the Joe Rogan Experience podcast was posted on YouTube, reaching 3.5 million views, in which Joe discusses the phenomenon (instead calling it "post nut syndrome").
37 images with the phrase have been posted on KYM, the earliest being from May 3, 2019 (below). Most were posted by KYM Collector Bot from Reddit, where the phrase is evidently popular in image macros.
