You learn something every day!
"Han shot first" is a phrase referring to a controversial change made to a scene in the science fiction film Star Wars (1977), in which Han Solo (Harrison Ford) is confronted by the bounty hunter Greedo (Paul Blake) in the Mos Eisley cantina. The change was made for the 1997 Special Edition re-release of Star Wars, and has since been altered twice more. The phrase "Han shot first" is meant to express that "Han was the only one who shot", and is a colloquial retort to series creator George Lucas's explicit cinematic assertion that Greedo shot first."
Lol! Nice research!