Is it a password, is it a joke or could it even be Russian code?
Donald Trump's cryptic middle-of-the-night Twitter sign off has sparked all of the above suggestions as the phrase "covfefe" went viral on social media.
The US president's unexplained word, which at first glance appears a typo, has inspired a fantasy Twitter spat, countless gags and - before you even look to cash in - been bought out as a website and sold as a t-shirt.
Here's the best selection of the reaction to his 5am tweet:
Could covfefe be an acronym?
Will he wake up and realise he misspelled coffee?
Is Trump speaking a different language?
Is it a (dangerous) code?
Covfefe inspires a host of memes and videos
It sparked warring wizards and vikings
Some enterprising folk looked to profit from the craze
Others found a new covfefe twist on old phrases
Finally, the most plausible: he misspelled coverage, didn't he?