I have a couple of "secure" passwords made up of 5 common(ish) words each
I had a real scare a couple years ago shortly after creating one of them, in which I thought I'd forgot it and locked myself out of my own computer. Thankfully after maybe half an hour I was able to recollect enough to figure it out.
Maybe I am just retarded.
But I wouldn't want to bet a substantial fortune on my ability to remember an exact progression of common words.