Not "may I use your cell phone" or anything of the sort. So I just said "no" (which was true, I had left it at home) and kept walking.
After I passed the group, he loudly said "Cracker". Keep in mind everyone involved in this is white.
After I got a little farther away, he rapidly repeated some phrase about a half dozen times increasing the volume each time. Best description I can make for this was that it sounded like an old time way to call pigs in for food.
There was too much of a generation gap for the insult to actually work - after the first exchange of words nothing they said even made sense to me.