The last time I EVER carried a knife with the pocket clip showing was years ago when I was in the service. There was a van on base that military volunteers would drive to help other soldiers get around base. Anyway, I was riding in in the van trying to get back to the barracks from the main gait, and we stopped by the bar on base to pick up a couple of the drunkies. Drunk soldier climbs into the seat behind me (and it was pretty late, so I'm dosing off a bit); he obviously saw the knife clipped to my pocket, and he managed to quickly grab it out of my pocket before I could stop him. He opened the knife and started threatening everyone in the van with it. Well, the driver and navigator happened to be M.P. so they took both of us to the M.P. station, and booked us. 1st sergeant had to come bail us out at 2am, and was not happy. I didn't really get into trouble, but drunky had to run back to the barracks in his civi cloths (still drunk) with 1st sergeant following behind in his car (it was at least 7 miles). He then got smoked for at least another hour back in the yard. I never got the knife back; it was the CRKT M-16 with titanium handle.
Now, I always keep my EDC completely concealed.