Role-playing other people's characters

Now it's come up in discussion, after I went on a murderous rampage on a guy for doing so, that I have some sever problems with people role-playing my character for me. I try to live by me "don't be a bitchy rper" motto and usually can put up with a little of this, but there is a line that can be crossed that we don't want to have crossed. One poor sap crossed.... as I was arguing with someone... and my tooth hurt. This is a dangerous combo and he was punished for it whether it was his fault or not. Regardless though there is something to be said about people who role-play other peoples characters for them and where the line crosses. I feel it's easiest to identify this problem when you start implying a role-players feelings that their character didn't have. This is clearly over the line, even if it is a safe assumption, the character's player ALWAYS dictates what their character is feeling. It's however not as easy to see that when for example, if your character holds out a chair for mine for you to not have to wait for my character to sit down before continuing with your posting. I find this acceptable, but this can be quite the mistake if they had something particular in mind like they were gonna fling the chair across the room and turn into a flying cat monster.

There's an easy way to avoid pissing off the possible flying cat monster role-player and that's to but the word that has been in your vocabulary forever IF! It's an easy way to skip over needlessly being over sensitive over their character's actions. Frankly if you find yourself in a situation where you're chewing you're fingernails praying to Zeus that you don't piss off the only role-play you've had for months here's a good way to deflect this fear and live on in fun. If you use if and they are still iffy about your role-play, fuck that loser.