This script was inspired by the above xkcd strip, this post by Jeff Preshing, and the letter D.
xkcdpass is a shell script, so drop it and the dictionary in the same place and make sure it's added
Just run xkcdpass and you will get a random four word password chosen from 5000 common english words.
xkcdpass scary cost couch thigh
You can also specify the number of words you'd like your password to be made of by passing the -l or --length option.
xkcdpass -l 6 walk office face bloody come controversy
If the you'd rather use a different dictionary, such as your machines word list, by passing the -d or --dictionary option.
xkcdpass --dictionary=/usr/share/dict/words cryptographist pseudograph amoebae overwhelmingness