The phrase comes from Granblue Fantasy, the fantasy role-playing series where Bahamut is a legendary dragon and powerful summon that players call upon in battle. A short gameplay capture turned the surprised exclamation into a standalone soundboard clip, where it now circulates among fans of the series and creators looking for a nerdy, over-the-top reaction. Because the name is instantly recognisable to players and the delivery is so theatrical, it still works as shorthand for awe at something impossibly strong or dramatic.