I have had a relatively small (1/8 inch, very narrow) pustule (I think) on the foreskin of my penis for a couple of years. It doesn t hurt and isn t bothersome, it is skin-colored but there is white, thick puss inside that I occasionally squeeze out with my thumbnail. It comes out like microscopic toothpaste. My wife suggested that I check it out with a doctor, which I will do. First though, I was hoping to understand what it might be.