South Korean actor Choi Min-sik who played the protagonist Dae-su in the thriller film Oldboy wasn't afraid to try anything to portray his character convincingly. He lost and gained weight depending on the filming schedule. He also trained for his role and was able to do most of the stunts by himself.

One of the most extreme things he did was burning himself with a hot wire because he didn't trust makeup artists to make the burns look real enough.

Another thing that not everyone would be brave enough to do is eat a live octopus, let alone four. That is how many Choi Min-sik ate, because he had to do four takes of the scene. This is real dedication, as the actor is vegetarian and a Buddhist, so he apologized and said prayers for each of the octopuses before eating them.