The joke leans on the absurdity of famously hostile fandoms agreeing on anything, and the 2025 film gave them a shared target throughout late August 20261. Posts pulled from wildly different corners of the internet: Hazbin Hotel demons dapping up Five Nights at Freddy's animatronics, Invincible fans crossing over with Steven Universe stans, and anime shippers linking arms with My Little Pony bronies1.

Older users noticed the setup borrowed heavily from the 2012 Tumblr 'Fandoms Grab Your Weapons' post, though the 2026 version swapped a rallying cry against a common enemy for a mock peace treaty3. The format spread fast because the film's exaggerated character names and sexual humor made it an easy shared punchline across otherwise unrelated communities1.

To make one, users typically grab a screenshot or fan art of two characters from opposing fandoms and stage a handshake, hug, or team-up pose, then caption it 'Just This Once' or a variation on the phrase3. The tighter the historical rivalry between the two fandoms, the sharper the punchline.