The phrase comes from SpongeBob SquarePants, the Nickelodeon animated series created by Stephen Hillenburg that premiered in 1999. The show uses illustrated time cards read by a French-accented narrator to jump forward in a story, with lines like one eternity later becoming running gags. The Spanish dub translated that card as una eternidad despues, and clips of the line spread online as a reaction sound for waiting, delays, and painfully slow moments in edits and memes.