Basically covert stutters do everything they can do to not stutter openly in front of people. World substitution is one strategy a covert stutter utilizes - when they feel they are going to block on a word they will quickly substitute it for a word that is easier to say. They will order food at restaurants based on what is easiest to say on the menu. They will avoid feared speaking situations like the plague (i.e, speaking on the phone). The problem with being a covert stutterer is you are not giving yourself the opportunity to overcome your fears and work on your speech. You are not living as your authentic self. Covert stutters find it hard to talk about stuttering with the people they are closest to, and will often never bring it up. It really is a crappy way to live. Source: I was covert for most of my life. Coming out of the stuttering closest is a process. What worked for me was attending a two week intensive program where I had to talk to my family and friends about stuttering, interview people on the streets about stuttering, learn to voluntary stutter to lessen the negative feelings I got from stuttering. Allowing yourself to stutter openly really is the first major step in overcoming stuttering or the fear that comes with it. Stuttering is what we do when we try not to stutter.