'Trzeba żelaza' comes from the Polish localisation of Stronghold, the medieval castle-building strategy game released by Firefly Studios in 2001 and known in Poland as Twierdza. The line is one of the game's terse resource warnings, spoken when the player's stockpile runs short of iron. Polish players adopted it as a shorthand joke for any shortage, and it circulates in gaming memes, stream clips and edit audios wherever a plan stalls for want of supplies.