The prime minister posted this photo of himself proudly watching astronaut Tim Peake blast off on Tuesday morning on his way to become the first Briton on the International Space Station.
But Cameron was forgetting an internet law as immutable as gravity itself: For every tweet of him watching TV, a piss-taking meme will instantly emerge.
Literally seconds after Cameron posted his photo, people started spoiling the historic moment. For example, here's the PM watching Babestation.
Here he is forgetting to switch over from ITV.
And here he is confusing Independence Day for the news.
For some reason, lots of people made lots of jokes about the prime minister and pigs.
We can't think what allegations they were alluding to.
No idea whatsoever.
But here's Cameron watching Ainsley Harriott pour some olive oil into a pan.
Here he is wrongly identifying a Pokémon.
He watched George Galloway do a little dance in a red leotard.
He enjoyed seeing Jeremy Corbyn dressed as Santa handling some mince pies.
The prime minister also enjoyed live updates from the launch courtesy of Balustrade Lanyard.
In fact, by the end of it all, everything got a little bit weird.
But, unlike in this photo from when he watched the London Olympics in a Team GB uniform, at least Cameron didn't dress up for the occasion and watch the launch in a spacesuit.
Jamie Ross is a Scotland reporter for BuzzFeed News and is based in Edinburgh.
Contact Jamie Ross at email@example.com.
Got a confidential tip? Submit it here.