Phimosis is something I am rather well read on as a consequence of me being a sufferer, well pretty much ex-sufferer but we shall get to that.
Basically phimosis is either the glans growing to big or the foreskin to tight (or both) with the result of a full (or in some cases even partial) exposure of the glans being impossible.
How common it is seems to very depending upon who you ask, apparently premature forceful retraction may cause it but that never happened in my case since I live in Britain.
I realised I had phimosis last year and felt rather silly for not realising earlier. It was fairly minor since I could expose about a third of the tip of the glans but the urethral opening was tricky to find and a full retraction was downright impossible. I saw a doctor while seeing him over an (unrelated) issue with my genitals and his first suggestion was a circumcision. I was appalled and he backtracked and offered me a prepuplastory which left me content but a little irked he had not offered that outright.
I feared for sensitivity in the foreskin being lost and so was hoping for some steroid creams instead but then I found this: http://www.cirp.org/library/treatment/phimosis/beauge/
Basically Dr Beauge found that, as Scrubs says, masturbation (or, rather the right sort
of masturbation) could cure phimosis, or perhaps that the incorrect variety caused it. Or visa versa.
Well, whatever, I decided to give it a go and keep an e-journaly of the events (it seemed like a supremely superior solution to surgery) which you can find here: http://www.beaugeblog.blogspot.com
but be warned: it contains some fairly, well, vivid descriptions of the process.
In short it worked, the thought of people who have not tried this being circumcised is most troubling to me.