Be wary when pulling your hand out of pants pocket, too. The very pointy blade on your folder may have opened just a bit, catching your finger while it's being removed from your pocket. Contact with said finger can cause the blade to open more, and engage finger ever deeper.
This - I've heard - can cause rather deep cuts which bleed profusely. No, no, I surely haven't experienced this; I just heard about it happening. Really. Honest.
jb