You could try the old aversion therapy of wearing a rubber band around your wrist, and giving yourself a really good 'zing' every time - you want the consequence to hurt more than the pleasure gained by doing the undesirable behaviour.
I have the same prob with swearing - for me, I think it's 'brain laziness', where I can't be bothered retrieving a more appropriate word from the old RAM - my "pleasure" would be about being able to be lazy.
I also used to have to put a quarter in the 'swear jar' -- when it got up to five bucks and I was STILL swearing...well, that strategy obviously wasn't working for me

so I gave it up.
I tried the rubber band with changing a pattern of thoughts, and it worked for that -- I was more motivated to make this change than to stop swearing, though.
Good luck!