Trump people sign their checks on the front. Hillary supporters sign their checks on the back. Protesters don't think it's fair that they don't get to sign as many.
I actually did that. Was very uncomfortable, but not painful. The night before my appt I had read about this in the UK and decided to try. It was interestinfg that I could watch the whole thing on monitor and ask questions. Wife did it with sedation and it took 48 hours to fully recover. After mine we did lunch https://www.ncbi.nlm.nih.gov/pubmed/9649011
Few of the NFL protesters are smart enough to understand the issues around their protests. They're basically just "joining-in under peer pressure... as virtue signalers". (The kind of thing Odumbo, Hellary, and the Left hopes all of us will do.) Disgusting!