The Spider-Man star uploaded a snap to his page showing him bare-chested and covered in body art, including a large black and white portrait of Emma on his neck.

James captioned the picture, "I (love) Hermoine (sic)," in reference to Emma's Harry Potter character Hermione Granger, but many fans failed to spot that he also tagged artist Cheyenne Randall in the post.

Cheyenne is known for using computer wizardry to add real-looking tattoos to pictures of celebrities, and the post appears to hint James' new inking is a fake.

James previously appeared onscreen with Emma in 2013 comedy This Is The End, about a celebrity house party which is interrupted by the apocalypse.

The film featured a star-studded cast of actors and singers all playing themselves - it also starred Seth Rogen, Danny MCBride and Jonah Hill, and there were guest appearances from Rihanna, Channing Tatum and the Backstreet Boys.

Emma previously revealed she did not understand the script when she first read it.

"I thought it sounded crazy," she said. "I remember trying to get my head around it on the phone to my agent who was like, 'So, it's Seth Rogen and Jonah Hill and James Franco and Danny MCBride and all these other comedians... And all the actors are playing themselves, and it's going to be the end of the world... and they want you in the movie'.

"I'm like, 'What? Why? How?' I had so many questions. I just remember reading it and thinking it's hilarious, I thought it was the most crazy, absurd premise for a story I'd ever heard. I had to do it."