To start the story, let me just say that I had modified the small pen blade on a Victorinox Tinker to a wharncliffe, since I tend to open lots of boxes. Working in apparel, lots of shipment comes in cardboard, and there's nothing quite like a wharncliffe blade to whiz through tape like it's not even there. It stays sharp with a touch-up on a ceramic stone every night.
My friend was turning 24, and decided to hold a get-together of old friends. We all got dressed up and had a nice meal of Indian food. While at the restaurant, she decided that it would be kind of fun to open up her presents at the dinner table, but discovered that some of the presents were tied up in ribbons, strings, stickers, and other things that can be a pain to get through without a sharp object.
Not thinking much of it, I pulled out my Tinker, opened the small blade, and passed it over for her to use. Now, after having been cut many times with a slipjoint, I should have warned her that these things don't have locking mechanisms, and that pressing up against the spine of the blade can cause it to close. However, the thought didn't cross my mind and so I sent it her way.
Perhaps she has never seen or used a wharncliffe blade before, but she started using the spine of the blade to try and slice through some ribbon, and luckily, her finger was not in the way of the blade. Gave her quite a scare though, and could've made for a bad birthday. At that point, I took back the Tinker and handed her something with a locking mechanism instead.