Believe it or not...it's the tiny knife in a "waiter's key" style corkscrew.
I have taken the knife out of one that I keep in my carry on bag....and of course it gets spotted by TSA when I am going through security at the airport. I let them look at it...they say it can't be taken on board, and I innocently ask why. "It's the knife!"....."What knife"? Oh...here you go.
Though every cork screw has that metal "screw" on it, which IMHO...is worse. But they let you on with that. Go figure.