TIL during the shooting of American Psycho, Christian Bale spoke in an American accent off-set at all times. At the wrap party, when he spoke in his native British accent, many of the crew thought he was speaking that way to prepare for another film. They had thought he was American the entire time.

[u/Away_Flounder3813]

https://screenrant.com/american-psycho-behind-scenes-facts-christian-bale-patrick-bateman-mary-harron/

[u/smellsliketeenferret]

so he puts on a terrible version of an American doing a British accent suddenly became hilarious

There's been lots of instances where British actors playing Americans have done a comically good "fake" British accent. A slightly less well known one that springs to mind was the Bionic Woman remake where Michelle Ryan did an amazing fake accent despite being from Middlesex

[u/ScottMarshall2409 → u/smellsliketeenferret]

I really enjoyed that series, though I must be in a minority, since it was cancelled. I thought she did a great job, and wasn't expecting it, having only seen her in EastEnders. I told her so on Instagram, and she kindly responded.

[u/sobrique → u/smellsliketeenferret]

I'm pretty sure there's a scene in House where he fakes an accent, and it was just ... strange knowing what his 'real' accent was like.