$ egrep '^[a-z]{4,10}$' /usr/share/dict/words | wc
      50768   50768  433477
    $ for i in `seq 5`; do egrep '^[a-z]{4,10}$' /usr/share/dict/words | shuf -n 4 | xargs; done
    droned engraves developer manoeuvre
    lifeforms lurked pursuing subjugated
    hooligans underplay sudden command
    quartettes soapbox blacklist pigtails
    roughening chefs mortals earthy

In my experience, things like that are both easier to remember and to type than things like fa#klwgjl5235 - I type sequences of English words far more often than I type anything else.