I grew up always having a small folding pocket knife in my pocket. After 9/11, I have lost so many small pocket knives that I don't even bother carrying one anymore. Likewise with corkscrews, a dozen of those are somewhere in the TSA/EU/AUS/Thai airport security bowels of contraband.

Never have I ever had any agent take something without asking. They identify it, ask me if I would like to go back and check it, and then offer to dispose of it for me when I let them.