Care to elaborate on this? How come using PGP insecurely is somehow more insecure than not using it at all? And what do you exactly mean by using it insecurely?

Care to elaborate on this? How come using PGP insecurely is somehow more insecure than not using it at all? And what do you exactly mean by using it insecurely? Care to give me an example of this insecure use of PGP?