I used to have a habit of getting waiters & waitresses to sign my cafe sketches. I think they enjoyed being part of the image and seeing what I had done to the place they clock in their 9 to 5's. I guess it also made the image more real as a place for me.
Others who'd spotted me were gladly included or on the rare occasion I'd approach some of the random people who were in the image for their John Hancock. But I fell out of habit. Mostly because some people had no idea what in the world I wanted from them or what my sketch was of. Also some others were a bit suspicious of giving out their signature, as we all should be.
Well-muscled man didn't have any qualms however, and was quite pleased to get a glimpse at what he looked like, as well as adding to the piece himself.