0x5f3759df is a magic constant that can be used to calculate the inverse square root of a number very efficiently. See this post for a detailed explanation. Now if you come across this number (which can happen anywhere, anytime), you will say “aha, I know that one”.
“We are a community of motherfucking programmers who have been humiliated by software development methodologies for years. We are tired of XP, Scrum, Kanban, Waterfall, Software Craftsmanship (aka XP-Lite) and anything else getting in the way of…Programming, Motherfucker.“