I gave in
https://trisquel.info/forum/new-user-root-password-problems#comment-62018 a
simple command line to choose a password in this way. Read the posts below
for a little discussion (with the math).
For six words (with no size limit on each word):
$ cut -d / -f 1 /usr/share/hunspell/en_US.dic | shuf | head -6 | tr '\n' ' '
You can execute the command repeatedly until it outputs a password you like.
Here are the five first passwords it has just output on my machine:
stupidness Hood quipping Henriette Martie unflappable
updraft Haskel Claudell neoplastic simulation blamelessness
appose musty angular brutalization syntheses spouse
copulative mommy construction Brueghel's cavalierness postural
hologram Andalusia digress Haslett pitchman wilderness
But, like one year ago, I still doubt my data are worth the time required to
break even a three word long password. And remembering six words is not that
easy. Easier than remembering a 10 random characters though!