If you allow multiple occurrences of the same word, you can get slightly higher entropy while making the passwords potentially even easier to remember.

    echo $(for i in 1 2 3 4; do shuf -n1 /usr/share/dict/words; done)

(Sorry, I'm not very good at bash, so this loop is probably not idiomatic.)

I don't think those words are very practical. For example, 4 consecutive runs produced:

shippon preannouncer half-hourly withgang egotize baffs chapter monolater photoengraver beachhead linguidental autoheader hazeled defloration exhumate barretries

none of which seem particularly easy to remember (or spell even).