Another photo and a comment about how it was made. This was shot on a tripod with a very wide lens (the above-mentioned M7 setup) and it's printed full-frame, so you should be able to realize how close I was. But I ended up with at totally candid photo composed the way I wanted it.
I initially had a discussion (debate, or maybe even an argument)about taking a photo, but they eventually agreed. I set up the camera and tripod, composed, and stood around holding a cable release and ignoring the viewfinder. Over time, they stopped paying attention to me, but someone came along that knew them and started talking to them from behind me. I just snapped the cable release. It's that simple.
I think for people who are willing to be photographed, it's a lot easier to be obvious and wait for the right time. You're better positioned and can be much more aware of what is going on.
By the way, they're barbecuing sheep heads on a bed frame.