Happenis (pronounced Happiness) is the erection of a penis. Men are typically not held accountable for their actions as this condition usually leads them into relationships that otherwise they would avoid.
“What is happenis? I have a hard on… then yes - this must be love”.
Short-hand for the word floccinaucinihilipilification, meaning the estimation of something as valueless (encountered mainly as an example of one of the longest words in the English language).