It's not clear. It's said in a low voice. But, in the opinion of many who have listened to this publicly available version of a 911 call made shortly before he shot unarmed Trayvon Martin to death last month, George Zimmerman seems to be saying "fuckin' 'coons." I also think he says that right at 1:50-1:52. So do many other people who have listened repeatedly. Just a whisper. But a hateful whisper. A whisper that, if it is what it sounds like it is, could put Zimmerman's actions into an even worse light than they already are. That racial slur has a long, ugly and infuriating history.
We know for certain that the 28-year-old Zimmerman, who has been identified as the "captain" of an unregistered neighborhood watch group in some reports, made other comments in that 911 call that could, in context, be considered racially charged. For example, "These assholes, they always get away."
But some people have said Zimmerman is saying something else. Some say they don't hear any words at all. Only an audio forensics expert can clear it up. Perhaps one already has and it will be presented as part of the evidence the grand jury and the U.S. Department of Justice will consider in their investigations.
ZappoDave has a diary on this subject here that includes an audio test.