Like others here, I sort of go with the "sacrificial anode" concept. I always carry a Leatherman Micra in addition to a "serious" folder... if someone asks for a knife, I hand them the Micra, and they don't get exposed to anything that might "scare the horses". Similarly, I have an "office convenience kit" in my desk drawer with a small mirror, band-aids, dental floss, analgesics, sewing kit, Fixodent (loose crowns, bridges, especially temporaries), safety pins, Photon 2 (personally, I prefer the 3), nail clippers, plastic bags, etc. This has nothing to do with my PSK or the larger set of stuff in the car out in the lot. I only reveal the serious gear for serious situations.

Along those lines, I should mention that I have for years kept a Ka-Bar "Hobo Set" in my desk drawer. This is a velcro/nylon pouch containing an all-stainless folding knife/fork/spoon combo. The interesting thing about this set is that each utensil detaches so that it has it's own handle, and you can actually eat in a civilized manner... and, as a side benefit, you have, in the middle, a VERY flat, slender, very lightweight lockblade folder in a very innocuous-looking package and context.