You can't see it here but this guy had one sleeve rolled up, and one fully down, which would annoy me. I did several sketches of him and his family. His partner had left him with their baby whilst she went to get drinks. He gamely played 'bang the stool' with the toddler for a while, thump thump thumpthumpthump, but there was more than a hint of relief in the speed with which he swapped the tiny child for a cup of coffee when she returned.
I have to say, reading that back, that I am never sure if my sketching is just sketching, or some kind of sanctioned voyeurism. People watching is, without doubt, endlessly fascinating.