I have always gone with the theory that, if your character does something stupid in an RP, the player is expected to have some balls and roll with the punches, to get his character out of trouble or else to gracefully accept the consequences of the player's stupidity in-game.
But what about when the player's ineptitude makes the character do something that is ridiculous or out of character for the character?
I was in such a situation once, and I felt so embarrassed and ashamed by my own ineptitude that I could not finish the joint post. The more I wrote on the JP, the less and less I liked it, to the point where it just became disgusting to me, to have my character appear to be so stupid and unprepared for something that, in retrospect, he should have been prepared for. It was also glaringly clear in the JP that neither my co-writer nor I had planned the thing or discussed it beforehand; we had simply begun writing it. That in itself was the MOST stupid thing. My co-writer presumably thought that I was as smart as he was and, well, I'm not. By the time my co-writer started his character's part and I saw the vast difference in our characters' reactions, I was so embarrassed at having been an idiot, that I could not bring myself to say to my co-writer, "Whoa, wait a minute. We need to stop this and coordinate things better."
That bit of weakness was my fault. I saw a problem and didn't feel confident enough to stand up for myself and for the story. I felt that, because it was RP, I had to accept the consequences of my own foolishness, even though those consequences killed the joy of the story for me.
The writer in me, though, was extremely dissatisfied with that. I wanted to say to my co-writer, "Look, this is turning into crap. Can we please stop this, agree on how our characters are going to handle the situation, and then re-write it so that they act in a unified and coordinated fashion?"
But are you allowed to do that in RP? Can you re-write without seeming like a weenie who can't take what is dished out?