Most of you probably know of butterfly knives, also called balisong.
You've most likely seen some bad guy flipping them around in some 80's movie.
When I first laid my hands on one friend's knife many years ago, he quickly showed me the most common trick for opening it which I spent the afternoon trying to master.
Next time I saw him, I was the one showing how to do the dozen or so tricks I had learned or invented.
There is a huge online community dedicated to the love of those particular knives, and the many flashy tricks you can use to open, close, or just juggle them.
Flipping balisong is an impressive, not that hard, and only moderately dangerous hobby (well, it at least depends on you how much risk you're willing to take in learning any given trick).
In this article I will give you some leads on how to get into this very accessible hobby, that will surely impress your friends.