The four stages of revisiting your old code: shock, disbelief, existential crisis, and finally the crushing realization that past-you was a complete psychopath.
First it's "Why would anyone write this abomination?" Then slowly the horrifying truth dawns on you - you are the monster who created this nightmare of nested if-statements and variables named 'temp1', 'temp2', and the classic 'finalFinalREALFINAL'.
The worst part? That moment when you finally understand your own twisted logic and think "Oh, that's actually kind of clever" - right before realizing you now have to maintain this clever monstrosity for another year.