Post nut clarity
The sudden feeling of unsullied, clear thinking you feel after sexually climaxing.
This happens because when you finish masturbating and climax, you have no more lust or temptation on your mind and you can finally think clearly.
It can also be a negative feeling, for example, you have been masturbating to porn that you would not normally view morally acceptable, but was blinded by your libido, and only realize how “bad” it was after you climax.
Origin of the term
The term “nut” or “to nut” comes from the phrase “to bust a nut”. The “nuts” would originally refer to a mans testicles, first dated in 1915. When you bust a nut, you release what is inside, similar to what happens when a male ejaculates.
Therefore “to nut” is associated with male orgasm.
However, “post nut clarity” is not a new phenomena, it has been known for generations. In French there is a phrase: “Le petit mort”, which translates to “The little death”, referring to the change in consciousness post-orgasm.
Spread of the term
The feeling of “post nut clarity” is known by most men, but opposed to what the term indicates, it happens to women too.
It is a popular slang on the internet, often associated with coming up with great realisations or ideas post-climax, and there are multiple specific subreddit threads regarding the topic.