II can sneeze upwards of 17 times in a row.
I don't envy that one! Five or six times is bad enough.
Its not much, but I can get a Runners High (http://www.lehigh.edu/~dmd1/sarah.html), usually much quicker then most.
I never really liked running, but once your Endorphins kick in, it feels like nothing can stop you. One of the greatest feelings in the world.
I tend to be at the opposite end of the scale and don't get any sort of endorphin rush
at all. I've found that physical exercise has always been a rather miserable and depressing pursuit.
In terms of what I do have, my joints are quite bendy and I have a degree of double-jointedness (though not my elbows as in the OP's example, which was rather freaky). Less so with age, though I still seem to be more flexible than most people.