According to this SarcasticGamer piece 733t haxxors VladsBoys have uncovered a dumped mission in the leaked GTA IV code called "Hot Coughing".
Apparently the mission didn't make it into the retail version. From the site:
Hacker R*Fan4Lyfe noted in a forum post that while the audio files for the mission were not included in the disc image (and presumably are not on the retail disc either,) the subtitles for the mission dialogue were still present. The mission involves Niko going to the hospital after pulling a groin muscle in one of the game’s side missions; a mission that is actually present in the retail game. While in the hospital, Niko is hounded by an ambulance chasing attorney humorously named Jerk Thompson. The attorney pesters Niko about his accident, trying to convince him that violent cartoons such as Tom & Jerry or Looney Tunes were to blame. The attorney is apparently reluctant to leave as the doctor examines Niko. Niko is finally able to get him to leave as the doctor performs the stereotypical “turn your head and cough” test to check for a hernia. As Niko turns his head to cough, he apparently spies the attorney gazing longingly at Niko through a gap in the curtain and that’s when all hell breaks loose.
We're saying nothing. Prepare for some kind of nuclear incident on Monday.