I write something else. I'll write down a few notes as to how I think the scene should go, but otherwise I'll leave it alone.

Sometimes, when I'm really blocked, I'll write mindless porn. I have this ridiculous super porny WIP that I don't ever intend on posting. For some reason writing porn comes easily to me, so if I'm getting angry with myself because I can't write I'll type some more pointless porn until my brain is back in the writing mood and I can move on to the actual story I want to tell.