I thought I heard that some people bought a cheap arm sling to wear after surgery so people know not to "bump them."

In my every day life, people will tell a joke, grab my arm, squeeze it at the elbow, and then yank it down. WHY DO THEY DO THAT! UGH! I tell them afterwards to please not do that again as I have "arm issues." They feel bad but the damage is done.

Anyways, does a sling, even kinda draped on you, make people be cautious around you? Can you wear your arm in an actual sling like if you are in a tight spot or is that going to affect your self after surgery?