In Arizona, a friend and I were in a convenience store between Prescott and Paulden on the way to Gunsite Training Center. My friend came from a state that then had no provision for private citiens to carry a handgun in any fashion, and was luxuriating in his ability under Arizona law to carry his custom Colt 45 auto in an exposed holster. I was a few steps away when I saw a man walk in, do a double take when he spotted the gun, and deliver a "target stare" to the loaded pistol. Amost in exaggerated pantomime, he mugged an expression of outrage and pointed at the pistol, making eye contact with others in the store that indicated his outrage. And then, that man moved in behind my friend, reaching out for the holstered pistol.
I stepped between them, glaring at the interloper. He stopped, looked at me, obviously decided that whatever was going to happen wasn't worth it, and walked away with an angry look on his face. I don't think he was going to try to shoot anyone with my friend's gun, but he was obviously going to grab it and do some show-off thing, which coulod have led to a struggle for a loaded gun in a crowded convenience store, with an obviously high potential for tragedy.