Used often to describe fan games adding more (and often very unnecessary) phases to an otherwise finished boss fight. Derived from the Undertale fan game, "Last Breath", in which its sub-community makes absurd amounts of fan made phases that exaggerate sans' durability and endurance to the point that it is a joke.
"Dude lets make vs tricky phases 5 and 6."
"Ever heard of Last Breath Syndrome?"
"No."
"Search it up."
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).