My thought is "who were the top four"?
Just like a bad news story reported here sometimes turns into a jokefest, I'm sure that's what these cops were doing. You'll get a pretty warped sense of humor after awhile working for the police or an emergency room. It's a coping mechanism. Notice, too, that it wasn't just white cops making these wisecracks.
For some reason today, everything seems to remind me of the Rodney King incident, possibly because the media played a large part in hyping that incident. It had an example of one of those 'warped sense' moments you referred to when Larry Powell, requesting an ambulance for Rodney described him as a "victim of a beating", followed by a nervous little laugh. The laugh was given quite a sinister connotation at trial, but was most likely one of those coping/nervousness things you described.