The one that was pointed at me by the motorcycle Cop.
It was a hot day in Columbia South Carolina (early 70's) and he told me that I had run a stop light. He also told me that I was trying to out-run him. When I realized his flashing blue light and siren was intended for my benefit. I stopped. He pulled his pistol and pointed it at my face. Most likely a 38 special but it was plenty big enough for me. He immediately got my attention. That was the most intimidating handgun I have ever seen.