Broly is a Saiyan character from the Dragon Ball franchise, best known as a hugely powerful rival to Goku, which makes this soft and uncertain hai especially funny by contrast. Online editors clipped the short line and began using it as a standalone reaction, separate from its original scene. Its popularity comes from that mismatch between Broly's intimidating reputation and the meek delivery. The clip now circulates in anime meme edits and soundboards as a quick reluctant yes, often placed under characters who clearly do not want to agree but do anyway.