I carry a knife almost everywhere. I regularly carry a 3" lockback (Spyderco Caly 3) but don't usually let anyone know I have it. I was at a work conference a few years ago and that morning I decided not to carry it, partly because I would be around all the company executives and didn't want one of the more skittish ones noticing it. What happens? My CTO needs to open a box and asks me if I have a knife. Arrgh.