Iron knee
Written as a placeholder for its homonym, irony. Intention of writing this way in arguments can be to ensure that the subject doesn't immediately catch on.
Guy 1. "Well I just think that if you judge people from what they say, you're a moron."
Guy 2. "You need to sit down and take care of that iron knee, dude?"
Guy 2. "You need to sit down and take care of that iron knee, dude?"